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U.S. GEOLOGICAL SURVEY CIRCULAR 1048 

-

An Enhanced Digital Line Graph 

Design 
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An Enhanced Digital Line Graph 

Design 

STEPHEN C. GUPTILL, Editor 

KENNETH j. BOYKO, MICHAEL A. DOMARATZ, ROBIN G. 

FEGEAS, HEDY j. ROSSMEISSL, and E. LYNN USERY, 

Contributing Authors 

A feature-based data model for digital spatial data bases that 

represent geographic phenomenon 

U.S. GEOLOGICAL SURVEY CIRCULAR 1048 
DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, Jr., Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Any use of trade, product, or firm names in this publication is for descriptive 

purposes only and does not imply endorsement by the U.S. Government 

UNITED STATES GOVERNMENT PRINTING OFFICE: 1990 

Free on application to the 

Books and Open-File Reports Section 

U.S. Geological Survey 

Federal Center, Box 25425 

Denver, CO 80225 

Library of Congress Cataloging in Publication Data 

An Enhanced digital line graph design : a feature-based data model for digital spatial data bases that represent geographic phenomenon I Stephen C. 

Guptilll, editor ; Kenneth J. Boyko ... [et al.]. 

p. em. 

Includes bibliographical references. 

Supt. of Docs. no.: 119.4/2:1048 

1. Digital mapping. I. Guptill, Stephen C. II. Boyko, Kenneth J. 

GA139.E54 1991 526' .0285-dc20 90-38767 

CIP 
PREFACE 

This circular is the result of several years of work on the part of a number 

of individuals. Within the National Mapping Division, two groups were established 

to study aspects of the DLG-E design. The first group, the Data Structures Study 

Team, consisted of Kenneth J. Boyko, Michael A. Domaratz, Robin G. Fegeas, 

David Hair, and Stephen C. Guptill. This group developed the basic components 

of the DLG-E data model and issued a report in November 1987. The second 

group, the Committee Investigating Cartographic Entities, Definitions, and 

Standards, was responsible for developing the domain of features for use with 

DLG-E. This group consisted of Hedy J. Rossmeissl, Michael A. Domaratz, John 

List, and E. Lynn Usery, with Robert D. Rugg and Stephen C. Guptill as advisors. 

The frrst report of this group was issued in November 1987, and a subsequent report 

was issued in April 1988. 

This circular attempts to consolidate the efforts of the two groups. In 

preparing the circular, various individuals focused their efforts on certain aspects 

of the work. Kenneth Boyko contributed to the data model activity and was 

instrumental in developing the representation rules and the example data set. 

Michael Domaratz, who was a member of both the data structure and the feature 

definition groups, was invaluable in developing feature representation rules and 

instance definitions. Robin Fegeas developed major portions of the DLG-E data 

model and its definitions and prepared the transfer specification and DLG-0+ 

implementations. Hedy Rossmeissl has been the focus of the feature definition 

activity and has labored to keep order in the face of chaos. Lynn Usery, now 

on the faculty of the University of Wisconsin, Madison, contributed to the feature 

definition methodology using the concept of world views. Although they did not 

directly contribute to this report, the efforts of David Hair and John List in the 

predecessor activities are gratefully acknowledged. In addition, Robert Rugg 

provided valuable assistance in developing the feature definitions by sharing with 

us his experience in developing the entity and attribute definitions for the .. Spatial 

Data Transfer Standard ... 

Stephen C. Guptill 

Preface Ill 

CONTENTS 

Preface Ill 

Abstract 1 

A new design 1 

Overview 1 

Evolution of the design 2 

Concepts of the DLG-E design 2 

Entities and features 3 

Objects 3 

Mathematical foundation of the spatial objects 4 

Attributes 4 

Relationships 5 

DLG-E data model summary 7 

Data model definitions 7 

Definition of DLG-E features 9 

Background 9 

Methodology for identifying features 9 

Five views 10 

Discussion of views 10 

Cover 11 

Division 12 

Ecosystem 13 

Geoposition 13 

Morphology 13 

Examples of feature objects 13 

Building 13 

Complex 13 

Road 14 

Representation of features 14 

Feature delineation strategies 14 

Rules for feature instances 15 

Basic features 15 

Named features 15 

Modeling constructs 16 

Modeling of network flows 16 

Vertical feature relationships 16 

Use of attributes 16 

Use of 11Underpass" 17 

Spatial extent 17 

Using the model to represent cartographic features 17 

Data model implementation 17 

Summary and future research 18 

Summary 18 

Future research 18 

Selected references 18 

Appendix A: DLG-E features A-1 

Appendix B: DLG-E example data set B-1 

Appendix C: DLG-E data model implemented within the spatial data transfer 

specification C-1 

Contents V 
FIGURES 

1-4. Diagrams showing: 

1. Example of an entity: Roosevelt Bridge in the "real world" 3 

2. Examples of objects: Representations of the Roosevelt Bridge 3 

3. Logical components of the DLG-E data model 8 

4. The five views and associated subviews 11 

TABLES 

1. Domain of attribute values for the attribute "operational status" 4 

2. The encoding of attribute values for a feature instance 4 

3. Example of attributes of attribute values 5 

4. Relationships between the objects of the DLG-E data model 5 

5. Dimensionality of "underpass" instance from intersection of features 17 

VI Contents 
An Enhanced Digital Line Graph Design 

Stephen C. Guptill, Editor 

Kenneth J. Boyk~, Michael A. Domaratz, Robin G. Fegeas, 

Hedy J. Rossme1ssl, and E. Lynn Usery, Contributing Authors 

Abstract 

In response to increasing information demands on its 

digi~al cartographic data, the U.S. Geological Survey has 

designed an enhanced version of the Digital Line Graph 

termed Digital Line Graph - Enhanced (DLG-E). In th~ DLG-E model, the phenomena represented by geographic 

and ca_rto~r~phic data are termed entities. Entities represent md1v1dual phenomena in the real world. A feature 

is an abstraction of a set of entities with the feature descr~~tion e~compassing only select~d properties of the 

ent1t1es {typically the properties that have been portrayed 

cartograph1cally on a map). Buildings, bridges, roads, 

streams, grasslands, and counties are examples of features. 

A feature instance, that is, one occurrence of a feature is 

described in the digital environment by feature objects ~nd spatial objects. A feature object identifies a feature instance 

and its no~locatio_nal attributes.. Nontopological relationships 

are associated w1th feature obJects. The locational aspects 

of the feature instance are represented by spatial objects. 

Four sp.atial objects (points, nodes, chains, and polygons) 

and the1r topological relationships are defined. To link the 

locational and nonlocational aspects of the feature instance 

a given featur~ obje~t is associated with {or is composed of) 

a set of spat1al objects. These objects, attributes and 

relationships are the components of the DLG-E data ~odel. To establish a domain of features for DLG-E an 

approach using a set of classes, or views, of spatial entities 

was adopted. The five views that were developed are 

cover,. division, ecosystem, geoposition, and morphology. 

The v1ews are exclusive; each view is a self-contained 

analytical approach to the entire range of world features. 

Be.cause each view is independent of the others, a single 

po1n! on t~e surface of the Earth can be represented under 

multiple v1ews. Under the five views, over 200 features 

were identified and defined. This set constitutes an initial 

domain of DLG-E features. 

Manuscript approved for publication August 29, 1989. 

A NEW DESIGN 

Overview 

. . The U.S. Geological Survey has be.~n producing 

digital cartographic data in its Digital Line Graph (DLG) 

fo~at for almost a decade. During this time., the tasks for 

whtch the data are being used have becom~ increasingly 

diverse, placing information demands on the data that were 

not planned for in their initial design. 

In response to ';hese demands, the Geo~'>gical Survey 

(as both a data supplier and a data user) ha~ designed an 

e~hanced version of the Digital Line Graph, termed Digital 

Lme Graph- Enhanced (DLG-E). In simole terms the 

DLG-E begins with the topological model n~w used u; the 

Survey's present DLG data structure (USGS, 1987a) and 

builds a cartographic feature layer upon the topology. 

Features are the sum of our interpretations of phenomena 

on or near the Earth's surface. Buildings, l''idges, roads, 

streams, grasslands, and counties are exampl ~s of features. 

~~ feature ~~finition is open ended, allovring the deftmuon of additional features of interest. Th~ features are 

des~~bed using objects~ a~tributes, and relationships. In 

addition, the DLG-E will mclude data quali':y information 

based on the recommendations contained in "The Spatial 

Data Transfer Standard" (Spatial Data Trar<;fer Standard 

Technical Review Board, 1990). 

Sev~ral other major agencies that collect digital 

cartographtc data are also considering (or have implemented) new feature-based spatial data wodel designs. 

These agencies include the U.S. Bureau of the Census 

(Marx, 1986; Kinnear, 1987), U.S. Defrnse Mapping 

Ag~ncy (D7fense ~apping Agency, 1988, r. 99-100), the 

I~sutut Geographtque National (France) (Bernard and 

Piquet-Pellorce, 1986; Salge and Piquet-Pellorce 1986· and 

Salge, written commun., 1989), Landesve~essungamt Nordrhein-Westfalen (West Germany) (Earwinski and 

Briiggemann, 1986; and Briiggemann, written commun., 

1987), and the United Kingdom Orc.lP~ce Survey 

(Haywood, 1988, p. 116). This trend toward featureb~d data models signals an evolution in the design of 

spatial data bases and geographic information systems. 

A New Design 1 
Evolution of the Design 

One of the demands for change arises from the 

Survey's major system development activity called Mark 

II. Mark II will be a digital cartographic production 

system with the National Digital Cartographic Data Base 

at its hub. Information in the data base will reflect the 

data content of the National Mapping Program's standard 

map series. This information will be periodically revised 

and new graphic products generated using computerassisted cartographic methods. Maintaining the information 

required to support these processes is a driving force 

behind the design of an enhanced data model (Guptill, 

1986; Morrison and others, 1987). 

Numerous examples of user experiences with the 

existing DLG data could be cited to support requirements 

for change. Comments have been made on the restrictive 

nature of the current DLG attribute coding scheme and 

data formats. One shortcoming of the existing DLG data 

is that users cannot identify and retrieve individual real 

world features by name, such as Broad Brook Stream. At 

present, named features are not carried in DLG data. The 

Geographic Names Information System (USGS, 1987b) 

maintains a data base of named features, but there is little 

compatibility between the two sets of data. Clearly this 

deficiency needs to be corrected in any new data model 

design. Other issues related to flexibility, standardization, 

and compatibility require changes in data content, geographic coverage, accuracy, and consistency among data 

categories. Although these issues will be addressed in the 

specifications for DLG-E data products, they impact the 

design of the data model. 

Additionally, the growing sophistication of geographic information systems (GIS 's) and the increasing 

diversity of applications involving GIS and spatial data are 

beginning to demand a more flexible and comprehensive 

model for spatial information. This linkage between GIS 

capabilities and the need for more advanced data structures 

has been explored by Goodchild (1987). 

Translating requirements into data model/structure/format constructs first requires that these constructs be 

defined and placed in context The following framework 

itemizes levels of data abstraction (based on Peuquet, 

1984). These levels can serve as steps in refining a design 

to meet a set of requirements. 

Reality is the total phenomena as they actually exist. 

Data reality is an abstraction of reality that includes 

only those entities thought to be relevant to anticipated needs. It is a definition of the scope of the 

data. 

A data model specifies the sets of components and 

the relationships among the components pertaining 

2 An Enhanced Digital Line Graph Design 

to the specific phenomena defmed l7 the data 

reality. A data model is independent of specific 

systems or data structures that organize and manage 

the data. 

A data structure specifies the logical orranization of 

the components of a data model and th ~ manner in 

which relationships among component:~ are to be 

explicitly defined. 

A file structure is a set of rules that specify the 

logical implementation of a data stru~ture within 

computing system environments. 

Note that the data model is concerned vrith defining 

components and relationships among those components. 

The next level, data structuring, is the defining of how 

these components and relationships are org;:'~Jlized in a 

computing environment. An important point to note is that 

many different data structures may be generat~d from one 

model. The support of a wide range of user requirements 

dictates the development of a comprehensive data model. 

CONCEPTS OF THE DLG-E DESIGI• 

The underlying philosophy of DLG-E is to "view 

cartography as an information transfer pro~ess that is 

centered about a spatial data base which can b~ considered, 

in itself, a multifaceted model of geographic reality" 

(Guptill and Starr, 1984). DLG-E data form the contents 

of the spatial data base. The DLG-E featrres must be 

representative of a model of geographic reality. 

The process of creating a representation of geographic reality. or more accurately of our conceptualization 

of reality, is variously referred to as semantic data modeling, knowledge representation, semantic netv·<>rk description, or, perhaps more broadly, conceptual n''Xieling (the 

various terms have evolved from work in artificial intelligence and data base management research; see Winston, 

1984, or Brodie and Mylopoulus, 1986). Usi"l'g the terminology of conceptual modeling, the world is comprehended 

in terms of conceptual objects or entities, which have 

associated descriptions and are related to e--ch other in 

meaningful ways (Borgida, 1986). To expres:- these ideas, 

researchers have developed a modeling fra"V\ework that 

includes the concepts listed below (adapted f~<>m Borgida, 

1986, and Borgida and others, 1986): 

A model is described as a collection of object 

descriptions. 

Objects in the model correspond to e"'\tities in the 

world. 
Objects are grouped into classes. 

Every object has zero or more attributes/properties 

which relate it to other objects. 

Classes are also objects. Classes, therefore, are 

instances of other classes, sometimes called "metaclasses" and may have their own attributes. 

Attributes can have multiple values. 

These modeling concepts have been used in the development of the DLG-E data model. 

Entitles and Features 

A real world phenomenon that is not subdivided into 

phenomena of the same kind is termed an entity. For 

example, a bridge is an entity that exists in the real world. 

Although it has component parts such as a superstructure 

and deck, it cannot be divided into components that are, 

themselves, bridges. 

A feature describes a class of entities, defmed by a 

selected set of common attributes and relationships that are 

properties of the corresponding entities. All of the 

elements of this set of phenomena are homogeneous with 

respect to the set of selected common attributes and relationships used to define the feature. Spatial data bases 

and maps are a collection of spatial and nonspatial information about selected features, attributes of the features, 

and relationships between the features. All geographic 

features implicitly have location as a defining attribute. 

For example, consider a "bridge." A bridge is one 

of a number of built-up structures on or near the surface 

of the Earth. The entity "bridge" is the erected unit in the 

real world (fig. 1). A bridge may be further defined to be 

a structure erected over a depression or obstacle to carry 

traffic. Thus, the feature "bridge" (describing a class of 

real world entities) is an element of a set of phenomena 

("erected structures") with the common attributes of 

function ("to carry traffic") and location. It also has the 

common relationship of spanning another feature ("over a 

depression or obstacle"). 

Figure 1. Example of an entity: Roosevelt Bridge in the 

"real world." 

A feature instance is an occurrence of a feature and 

has a unique set of attribute and relationship values. 

Expanding on the bridge example, the featt·re instance of 

a bridge (the Roosevelt Bridge) has unique values for the 

attributes function (vehicle traffic) and location. It also has 

unique values for the relationship of passing over another 

feature (spans the Potomac River). 

The resolution, or level of detail, of a domain of 

defined features may vary between classification schemes 

created by different organizations. These differences in 

resolution are due to differences in the set of phenomena 

and common attributes and relationships used to defme the 

features. For example, one could create "hig'ler resolution" 

features such as "covered bridge" and "unccvered bridge," 

which are subsets of the feature "bridge," by modifying the 

set of phenomena to "an erected enclosed sb'Ucture" and to 

"an erected exposed structure," respectively. Conversely, 

one could create a feature that includes bridge as a 

member of a superset by modifying the o~fmition to "a 

structure built to carry traffic." This encompassing feature 

would include bridges and tunnels as memt ~rs of the set. 

Objects 

Objects, along with their attributes and relationships, 

describe the characteristics of feature instarces. For the 

bridge example, the objects on a map graphic might 

include point, line, and area symbols and rssociated text. 

Alternatively, the objects might be a collection of records 

in a file of digital data (fig. 2). 

)----[~ Roosevelt Bridge 

Feature: Bridge 

Attributes: 

Covering: 

Name: 

Number of decks: 

Operational status: 

Graphic Object 

Not covered 

Roosevelt Bndge - To Component 1 Spatial Objects 

Operational 

Digital Objects 

Figure 2. Examples of objects: represe.,tations of the 

Roosevelt Bridge. 

The objects in the digital environmel'lt are used to 

represent both nonlocational and locational aspects of the 

feature instances. A feature object is an element that 

identifies the feature instance and its nonlocational attributes. Spatial objects are elements used t1 represent the 

location of a feature instance. The spat~m objects are 

defined for zero-, one-, and two-dimension~l objects. To 

be mapped, a feature object must be associated with one 

or more spatial objects. In a few cases th~ location of a 

Concepts of the r',G·E Design 3 
feature object may be unknown and thus not reference any 

spatial objects. 

Mathematical Foundation of the Spatial Objects 

The objects used to represent the spatial components 

of the DLG-E data model are formally described using 

terminology from graph theory. The DLG-E data model 

uses a directed, planar graph (more precisely a pseudograph) composed of vertices, edges, and faces to describe 

spatial objects. See, for example, Harary (1969) for an explanation of these terms and the concepts of graph theory. 

The graph G consists of a nonempty set V(G) of 

vertices, where V is a finite set of points in real vector 

space R2 with one point per vertex, together with a 

prescribed set E(G) of ordered pairs of (not necessarily 

distinct) vertices of G. Each pair e = (u,v) of vertices in 

E is an edge of G, and e is said to join u and v. The 

graph is a plane graph in that the edges intersect only at 

their vertices (the edges are simple curves). The degree of 

a vertex vi in graph G, denoted deg vi, is the number of 

edges incident with vi. The regions defined by the plane 

graph are called its faces, the unbounded region being 

called the exterior face. 

Synonymous terms exist from geometry and topology 

and are often seen in the literature. Synonyms that have 

been used for vertex include point, node, 0-cell, junction, 

0-simplex, and element; synonyms for edge include line, 

arc, 1-cell, branch, 1-simplex, and element. Books by 

Bondy and Murty (1976), Giblin (1977), and Lefschetz 

(1975) provide additional information on graph theory and 

topology. Corbett (1979) gives some insights on the 

topological principles used in cartography. 

In order to conform with the terminology used in the 

proposed Spatial Data Transfer Standard (SDTS), the 

corresponding terms from SDTS and the mathematical 

terms described here are given below: 

SDTS terminology 

Point 

Node 

Chain 

Polygon, topological 

Graph theory 

terminology 

Vertex ( deg vi = 0) 

Vertex (deg vi ;:: 1) 

Edge 

Face 

The SOTS terminology will be used in the remainder of 

this document. The set of relationships between members 

of these object classes (point, node, chain, and polygon) is 

given in "Relationships." 

Attributes 

Attributes are the locational and nonlocational 

characteristics of the entities represented by the objects or 

4 An Enhanced Digital Line Graph Design 

of an attribute value. Locational attributes describe an 

object's geographic position (using x, y coordinates, for 

example) or a geometric characteristic (such as its accuracy). The nonlocational characteristics o~ an entity 

include such concepts as its operational status, name, and 

function. An attribute value is a measurement assigned to 

an attribute for a feature instance or for (anotl,~r) attribute 

value. These measurements are made from one of the four 

levels of measurement (nominal, ordinal, inter··al, ratio). 

A domain of nonlocational attributes is predefmed 

for each feature. In addition, a domain of attJibute values 

is specified for each attribute. An example of an attribute 

and its domain of attribute values is shown ir table 1. 

Table 1. Domain of attribute values for the attribute 

"operational status" 

Attribute: Operational status 

Attribute values: 

Abandoned 

Dismantled 

Operational 

Proposed 

Under construction 

Unknown 

For a particular feature instance, appropriate attribute 

values describing the instance are chosen for each attribute. 

An example of the attributes and associated attibute values 

for the feature instance of the bridge is given in table 2. 

Table 2. The encoding of attribute values hr a feature 

instance 

Feature: Bridge 

Attributes: Attribute values~ 

Covering: 

Name: 

Number of decks: 

Not covered 

Rooseve.lt Bridge 

1 

Operational status: Operaticnal 

Three special attribute values, "not applicable," 

"unspecified," and "unknown," are available fo· selected attributes. They are defined as follows: 

Not applicable: Used to describe a feE ture instance 

that cannot take on a value for a 

particular attribute. 
Unspecified: 

Unknown: 

Used to value attributes of a feature 

instance for which the data collector does 

not provide a measurement. 

Used to note that an attribute could not 

be measured for a feature instance. In 

general, attributes having an attribute 

value of "unknown" will be resolved prior 

to the release of the data. 

Every attribute in the domain of attributes describing 

a feature must be assigned at least one attribute value. 

More than one value may be required for an attribute to 

describe a feature instance. For example, for an instance 

of the feature "road," the attribute "route designator" may 

have multiple values (route numbers). 

Attributes may also refme other attribute values. For 

example, the feature "well" has the attribute "product." 

An instance of the feature might have the value "water" 

for this attribute. The attribute value "water.. is further 

modified by the attribute .. water characteristics," which 

could contain a number of values as shown in table 3. 

Table 3. Example of attributes of attribute values 

Feature: Well 

Product: 

Gas 

Heat 

Oil 

Water ------> Water characteristics: 

Alkaline 

Hot 

Mineral 

Salt 

Features are represented as they exist at a given 

instant of time. Any temporal data are given as attributes 

of the feature objects. Appendix B contains examples of 

feature instances fully encoded with attributes and attribute 

values. 

The spatial objects of the data model are defined for 

two dimensions upon a surface. Thus, the locational 

attributes for the spatial objects are limited to the definition 

of the surface upon which the zero-, one-, and twodimensional objects occur. The coordinate data associated 

with a spatial object reflects that object's position on the 

surface of the Earth. For example, a section of road may 

be represented by a chain with x, y, z coordinates as locational attributes. The z coordinates reflect the surface 

elevation at the x, y location. Such z coordinates are 

optional in DLG-E. If a feature is elevated above the 

surface, that elevation measure is associated with the 

feature object. Other elevation values, such as the elevation of the surface of a pond, are also con~idered to be 

attributes of the feature object. 

Relationships 

Relationships define the topological an~ nontopological links between objects. They are used wit"-in the model 

to describe not only the topological relatio"'~ships of the 

elements of the graph but also the relationrhips between 

feature objects and spatial objects and ber.ween feature 

objects and other feature objects. Relationrhips are also 

used to model various aspects of spatial inf0rmation that 

cannot be inferred from the spatial objects alone. The 

relationships between model components curnntly used are 

listed in table 4. The relationships listed are between 

members of the object classes and not betwe~n the classes 

themselves. 

Table 4. Relationships between the objects of the DLG-E 

data model 

Object class Relationship Object class 

feature ----composed of---> * 

<---part of-------

feature ----boWlded by----> feature 

< ---boWldS--------

feature ----inflow from---> feature 

<--outflow to-----

feature <--connected to---> feature 

feature --vertically related to--> feature 

point ----within-------> polygon 

<---contains------

node ----bounds--------> chain 

<---bounded by----

chain ----within--------> polygon 

<---contains------

chain ----boWlds--------> polygon 

<---bounded by----

*Any of the objects (feature, point, node, chain, or face) can be used 

in this relationship. 

The relationships between feature objr~ts are further 

described as follows: 

"composed of/part of': Describes th~~ formation of 

feature objects from feature objects and (or) spatial 

objects. Can be used to aggregate either disjoint or 

Concepts of the O'._G·E Design 5 
adjoining spatial objects or feature objects. Example: Lake Michigan is part of the Great Lakes. 

"bounded by/bounds": Describes the limits of the 

contiguous spatial extent that limit all or part of a 

given areal feature. Consists of a "boundary feature" that is an outer ring of chains containing the 

feature and inner rings that bound areas ("holes") 

that are not the feature. Example: Fairfax County, 

Va., is bounded by a boundary that is composed of 

a set of chains. One subset of chains defines the 

outer boundary of the county, and other subsets 

define holes in the county, such as the set of chains 

that denotes the limits of the Town of Vienna, a 

jurisdiction that is spatially within the outer boundary of the county but politically a separate entity. 

"inflow from/outflow to": Used to model flows 

through networks in the cases where the network 

links are represented as areal features. The inflow 

and outflow relationships represent the source and 

discharge locations (that will be represented by a 

feature termed a "junction") for modeling network 

flows. Example: Where the Potomac and Anacostia 

Rivers (each represented by areas) meet, a junction 

is formed and the information that the water from 

the Anacostia River flows into the Potomac River is 

recorded using the inflow from and outflow to 

relationships. Also used with the feature "connector" to model flow through a network in cases 

where flow is known to exist, but the location of 

the objects are unknown. 

"connected to": Similar to the inflow and outflow 

relationships but used where the flow is bidirectional, alternating, or unknown (as in the case of a road 

that is wide enough to be represented as an area). 

"vertically related to": Used to link an instance of 

an underpass feature with the features that created 

the instance. The ordered relationship preserves the 

information that the frrst feature is "on top" and the 

second is "on the bottom." 

The relationships between spatial objects consist of 

the boundary /co boundary topological relationships. These 

relationships were discussed in "Objects" and are defined 

in "Data Model Definitions." Note that the topological 

relationships of the spatial objects do not reflect any 

feature relationships. For example, the fact that a point 

(representing an oil tank) is contained in a polygon (representing an airport) does not necessarily define any relationship between the features that those spatial objects represent. A definite relationship between the oil tank and the 

6 An Enhanced Digital Une Graph Design 

airport should not be assumed unless a specific relationship 

gives the information (for example, an indication that the 

oil tank is owned by the airport). 

The most prevalent feature relationship is the "composed of' relationship (road A is composed o4:' chains 1, 2, 

and 3) used to form the geometric representation of a 

feature instance from a set of spatial object:~ (which can 

also be done indirectly through other fealure objects). 

Other relationships between feature objec+~ could be 

defined to describe situations such as r1ministrative 

hierarchies (the Town of Vienna, spatially contained within 

Fairfax County, is not part of the county's police jurisdiction). For flexibility and expansion, the m'Xlel is open 

ended with respect to the addition of new re .~tionships. 

Note also that relationships can have at~butes. One 

use of attributes of relations would be to de~cribe the set 

of members included in the relation, particu ~ly if those 

members were to be considered in an ordere-t or directed 

sense. For example a road might be c01rryosed of an 

ordered set of chains, or a stream composed of an ordered 

and directed set of chains. Chains are ordered in a linear 

sequence, with no branches, when chain (i+l) of the set 

has a common node with chain (i), and chai"' (i+2) has a 

common node with the other node of chain (i+ 1), and so 

on for each chain in the set The elements are directed 

when a mechanism exists to arrange the cha~n set so that 

the end of one chain corresponds to the strut of the next 

chain in the set. There is no requirement for all the 

coordinates in the chains in a directed set tC' be similarly 

sequenced, as long as some mechanism exists to record the 

"sense" of each chain being referenced ("forward" or 

"backward"). 

The representation of flows through a network and 

overpassing/underpassing features may requirr. such attribution of relationships. For example, given f~ature objects 

composed of chains, the chains are to be considered as an 

ordered set having uniform direction. The dir~~tion is indicated by an attribute describing the direction for traversing 

the chain. In addition, a real world (ground) significance 

to this direction is indicated by attribution of the feature 

object. For the underpass, the relationship is ordered, with 

the first feature object overpassing the secon·t Under the 

present design, these are the only cases that utilize 

attributes of relationships. Any other ca~es requiring 

attribution of relationships are proposed to te handled by 

attributes of feature objects. 

In another, hypothetical usage, attributes of relationships might be used to describe the accurac:· of a spatial 

object, a chain, that represented both a road segment and 

the edge of a forest. The locational accuracy for the road 

is different from the locational accuracy of the forest edge 

(the edge being a gradual transition zon~ or "fuzzy" 

boundary). The respective accuracy figure could be used 

as an attribute on each instance of the "com:r<1sed of' relationship. 
DLG-E Data Model Summary 

Features are the sum of our interpretations of 

phenomena on or near the Earth's surface. The components of the data model used to represent these features 

are objects, attributes, and relationships. Objects are the 

basic units of representation of the encoded phenomena. 

Attributes are the locational and nonlocational characteristics of the entities represented by the objects. Relationships are the links between the objects. Taken collectively, these objects, attributes, and relationships constitute 

the DLG-E data model. 

Various logical components of DLG-E are shown 

diagrammatically in figure 3. The locational components 

of a feature instance are described by the spatial objects: 

points, nodes, chains, and polygons, or combinations of 

these objects. The spatial objects have a set of locational 

attributes, typically a set of coordinates that characterize 

their location in space. These consist of x, y, and optional 

z coordinates. A feature object identifies a feature instance and its nonlocational attribute. 

A given feature object may consist of other feature 

objects. A given entity may always be represented as one 

feature object. However, for the representation to be 

complete, one or more spatial objects must also be associated with the feature object either directly or through other 

feature objects. Flow and connectivity information is encoded through the ordering of chains and the relationships 

of the features. Additional flow characteristics are nonlocational attributes of a feature instance. These constraints bound the data modeling task. 

Data Model Definitions 

The following definitions describe the components of 

the DLG-E data model. In some cases they replicate or 

further refine the definitions of cartographic objects given 

in "Spatial Data Transfer Standard." 

Entity: A real world phenomenon that is not subdivided into 

phenomena of the same kind. 

Feature: A class of entities with common attributes and 

relationships. The concept of feature encompasses both 

entity and object. 

Feature instance: An occurrence of a feature defmed by a 

unique set of attribute and relationship values. 

Object: A digital representation of all or part of an entity. 

Feature object: An element that identifies a feature instance 

and its nonlocational attributes and relationships. A 

feature object may consist of other feature objects. The 

locational aspects of the feature instance are represented 

by spatial objects, either directly or through other feature 

objects. 

Spatial object: An element used to represent 1 'lcational attributes and topological relationships of a feature instance. 

Spatial objects are defmed for zero, one, and two 

dimensions. Data for the third dimension are limited 

spatially to the definition of a surface upon which the 

zero-, one-, and two-dimensional objects occur. 

Attribute: Characteristic of a feature or of an attribute value. 

Attribute value: Measurement assigned to arr attribute for a 

given feature instance or for (another) attribute value. 

Locational attribute: An attribute that describe;"- the geographic 

position of a feature instance; locational attributes are 

assigned to a spatial object. 

Nonlocatlonal attribute: Characteristic of a feature instance or 

attribute value other than location. 

Relationships: Linkages between objects. 

Topological relationship: Boundary/cobound"ry relationship 

between spatial objects. 

Nontopological relationship: Relationships between feature 

objects and (or) feature objects and spati,.l objects. 

Graph: A set of topologically interrelated zero-dimensional 

(node), one-dimensional (chain), and sometime twodimensional (polygon) objects, conform~:qg to a set of 

defined constraint rules: each chain is bounded by an 

ordered pair of nodes, not necessarily disf"lct; a node may 

bound one or more chains; and when r~alized in vector 

space, not more than one node may ex~~t at any given 

point, and chains may not intersect (e:vcept at nodes). 

(SDTS definition) 

Node: A zero-dimensional object that is the ju ... ction of two or 

more chains or is an end point of a cha:n. A node is a 

component of one and only one graph; ar such, it may be 

located at one and only one point, and if so located it 

must be the only node of its graph located at that point. 

(SDTS definition) 

Chain: A directed sequence of nonintersecting line segments 

with nodes, not necessarily distinct, at ea ~h end. A chain 

is a directed link (a one-dimensional object that is a 

connection between two nodes) with ge'.ometric location 

specified by a sequence of one or more Pne segments. A 

chain is a component of one and only on":\ graph; as such, 

a chain may not intersect itself or any other chains within 

its own graph. (SDTS definition) 

A chain may be contained within one poJygon of a graph. 

The topological relationships of such a chain are still 

defined by the dual two-element ordered sets of nodes and 

polygons; however, the start and end nodes must be 

different, and the right and left polygons must be the 

same. 

Polygon: A two-dimensional object of one and only one twodimensional cell complex (a graph and it:~ complement set 

Concepts of the r-,G•E Design 7 
METACLASS 

CLASS 

FEATURE OBJECT 

SPATIAL 

OBJECTS 

CLASS 

METACLASS 

is_a 

Figure 3. Logical components of the DLG-E data model. 

8 An Enhanced Digital Une Graph Design 

bounded 

by 
of polygons). The polygon is bounded by one or more 

chains of the complex. (SDTS Definition) 

Point: A zero-dimensional object that specifies geometric 

location. One coordinate pair or triplet (or equivalent 

locational attribute value) specifies the location. (SDTS 

Definition) 

DEFINITION OF DLG-E FEATURES 

Background 

The DLG-E data model has a variety of components for representing a feature. However, before 

describing how those components are used to represent any 

given feature, the domain of features (that is, !he data 

reality) to be described by the model should be dtscussed. 

The report "Proposed Definition of Cartographic Features 

for Digital Line Graph - Enhanced (DLG-E)" (April 

1988), by the Co~mittee Investiga~ng C~~aphic 

Entities, Definitions, and Standards, defmed an mttial domain of features. A synopsis of that work is incorporated 

in this report. In preparing the set of DLG-E features, the 

committee reviewed related efforts including those of the 

Digital Cartographic Data Standards Task Fo~ce (1988)~ the 

Defense Mapping Agency (1987), the Canadtan Council of 

Surveying and Mapping (1982), the Bureau of Land 

Management (1978), and the South African Natural 

Research Institute for Mathematical Sciences (1987). The 

current list of DLG-E features is given in appendix A. 

Methodology for Identifying Features 

Persons reading a map perceive features according 

to their needs and experiences. For example, one may be 

interested in the extent of a given named feature, such as 

the Potomac River or the Blue Ridge Mountains. Others 

may have a different interest and employ a different set of 

criteria. They may be interested in bicycling from Mount 

Vernon, Va., to Leesburg, Va., and would be concerned 

with a connected network of roads and trails between the 

two locations. In a digital environment, one attempts to 

explicitly encode information that best satisfies most users. 

The designers are faced with the problem of sp~ifying a 

set of information in a form that can be perceived unambiguously by the majority of users. This. sp~ification 

process can be viewed as a process of classtficatmn. An 

expandable method of classification is necessary when 

defining features. . . 

Classification involves the selection and groupmg of 

phenomena into classes on the basis of common properties 

or relationships. The selection of a classification system 

has implications beyond the definition of common names 

for things. It is the classification scheme that defmes the 

nature of the generalizations that are made about the 

phenomenon under study (Abler and others, 1971). Note 

the linkage between the classification of mzo features and 

the concept of the map as a model. As stated by Board 

(1967), "it is important to realize that they [maps] are also 

conceptual models containing the essence of some gener~­

ization about reality." In the map model, t~e charactenstics of the classification scheme and the rernlting features 

specify this essence of the generalization of reality. 

In the DLG-E feature classificatio, process, an 

approach was taken that initially subdivided the . world of 

geographic phenomena into five classes, termed views, th~t 

correspond to the major facets of i! model of geographic 

reality as described by Geological Survey renuire~ents an~ 

specifications. A view is defined as a syrtematic classification of a set of entities in which all merrbers of the set 

possess a common defining characteristic. T"'~ charac~ristic is specified explicitly in the ~efinitior of the vi~w. 

Views are similar to the geographical concepts of regiOn 

and spatial system (James and Jones, 1954; James, 1972) 

and "geographic matrix" (Berry and Marble., 1968). Common cartographic tenns such as category a"'d ~verlay are 

related to views in derivation but lack tln ngor of the 

defining characteristic. . . 

While views provide a methodology for classifymg 

features, it is the classification scheme tl"at defines the 

nature of the generalizations about the pher~menon under 

study. These generalizations are reflected in feature 

definitions. For example, a road is an entity that covers 

a part of the Earth's surface. In the DLG-E methodology, 

it is classified in a view called "cover," a view with the 

defining characteristic of material at a location on or near 

the surface of the Earth. Other feature~ in the view 

"cover" include "building," "bridge," "railway," and "grassland." A "county" is not a feature in thr. view "cover" 

because it is not covering material on the Earth's surface. 

A county is in the view "division" because it is a political 

entity independent of the actual material on or near the 

Earth's surface. Other examples of featur~ in the view 

"division" include "state," "city," "reser·ation," and 

"census block." 

New views are introduced in the mef"'fldology when 

an entity cannot be appropriately classified in existing 

views. For example, a contour line is an entity that does 

not fit the views "cover" or "division." A contour line 

reflects measurement data about the Earth's surface. The 

feature "contour" requires a view in whic"' measurement 

data are the focus. That same view is ne€'ried to classify 

features such as "control station" and "~oot elevation." 

Thus, a new view called "geoposition" that reflects entities 

of measurement was created. 

In an approach similar to creatin~ views, finer 

divisions of a view, called subviews, mar be created to 

further refine the concepts included in the view. The view 

and subview approach allows a user to fit unclassified 

Definition of Dl.G·E Features 9 
entities into the appropriate part of the schema. It also 

provides a framework for comparison to other sets of 

features as defined by other organizations. 

While the approach uses the concept of multiple 

views of the world and a hierarchy of subviews within 

each view, neither the views nor the hierarchy need be 

stored with feature data. Nor is it necessary to group the 

features into categories. The views and subviews are used 

only to define the domain of features. Alternative views 

will yield different features, and features within a single 

view can be modified or expanded. Users can apply other 

views or hierarchies to add new features to the list. Use 

of features in the domain and use of the data require 

limited information concerning the approach methodology. 

The views and subviews are illustrated in figure 4. 

This approach allows for expansion by creating a 

completely different view, adding new subviews, or 

augmenting the features within the existing five views. To 

classify a new entity, one would first determine whether an 

existing view, subview, feature, attribute, or attribute value 

is appropriate by comparing the characteristics of the new 

entity to existing defmitions in the domain. After making 

this comparison, the new entity would be placed in the 

correct level of the hierarchy either by creating new views 

or subviews, or by expanding the list of features, attributes, 

or attribute values. Some examples are given below. 

Large-scale mapping of base category information 

considers entities not currently listed in the domain as 

features. A specific instance is a .. curb... Examining the 

views, a curb would be classified as cover. Within the 

view "cover," the curb is considered to be in the subview 

"built-up land .. and a .. structure." In the subview "structure," entities are differentiated into features based on form. 

Examining the list of features under "structure," a curb 

does not fit any of the existing feature definitions, and, 

thus, a new feature must be created. 

A second example from a large-scale product is a 

single housetrailer with a permanent foundation. A 

housetrailer is a type of cover, built-up land, and a 

structure. The feature "building.. encompasses housetrailers, and the attribute "text" with a value of "housetrailer" is appropriate. An alternative would be to institute 

a new attribute such as "building construction type.. with 

one possible value being "housetrailer." 

Expanding the number of views can be used to 

encompass features such as those that occur on geologic or 

other thematic maps. A geologic or other thematic view 

would require complete generation of the hierarchy within 

the view and the development of a list of features and 

attributes for that view. The resulting set of features then 

becomes a part of the total list of features independent of 

the approach methodology and completely usable with the 

other features in the total set. 

10 An Enhanced Digital Line Graph Design 

Five VIews 

The current DLG-E model classifies selec.ted entities 

into five views on the basis of common defin~ng characteristics. The five views are cover, division, ecosystem, 

geoposition, and morphology. The views are exclusive; 

each view reflects a self-contained analytical approach to 

world features. Because each view is independent, a single 

point on the surface of the Earth can be represr.nted under 

multiple views, and features within any one view may 

coexist with features in the same or any other view. For 

example, examine the entity "boundary point... If a 

monument exists at the location of the boun 1ary point, 

then two features will be recorded in the data. The feature 

"boundary point," referring to the monumented location on 

a boundary, is in the view .. division" while the second 

feature, "point monument," denoting the stru~ture on a 

boundary line, is in the view "cover." Brief defmitions of 

the five views follow: 

Cover: Reflects physical or material fe'atures at a 

location on or near the surface of the Earth. While 

this view is based on form, at the lowest level 

features it may be differentiated by function. 

Division: Reflects cultural demarcations of the 

Earth's surface for a particular purpose or for 

separations resulting from human activity. 

Ecosystem: Based on climate, vegetatior, soils, and 

other controlling environmental factors thlt result in 

unique ecological units. 

Geoposition: Reflects measurement data about the 

Earth's surface and contains points or F11es on the 

Earth or its representation for which tl'~ location, 

relative to a particular datum, is well kr0wn. 

Morphology: Based on the form of the land. While 

a strict geomorphological interpretation o~ landforms 

based on process is inherent in the conto·~r information on Geological Survey maps, the act'.lal features 

must be interpreted. However, some of the features 

carry names and those features must be coded in the 

digital data. Thus, morphological features are those 

landform features that are named, labeled, or 

symbolized as distinct entities on current map 

products. 

Discussion of VIews 

The following section offers a more detrHed discussion of each view and includes definitions of subviews. 
Geographic Reality 

I 

Views: 

Subviews: 

Cover 

I 

I 

I 

Barren land 

Built-up land 

-Network 

-Structure 

-Complex 

-Agricultural 

-Commercial 

-Entertainment/ 

RecreationaV 

Memorial 

-Disposal 

-Extraction 

-High density 

building area 

-Industrial 

-Institutional 

-Residential 

-Transition 

-Transportation 

-Utility 

Cultivated cropland 

Vegetation 

-Grassland 

-Shrub land 

-Forestland 

Water 

Division 

I 

I 

I 

Administrative 

Boundary 

Census 

Hydrologic unit 

Land parcel 

Locale 

Maritime 

Political 

Survey system 

Figure 4. The five views and associated subviews. 

Cover 

The view of cover reflects physical or material 

features at a location on or near the surface of the Earth. 

This view contains a mixture of land use and land cover 

information. Multiple features derived from this view may 

occupy the same location. 

Because of the diversity in the features defined by 

this view, additional subviews were added to clarify the 

distinctions between features. There are five subviews, 

based on the land use and land cover terms and definitions 

recommended by the Department of the Interior Land Use 

and Land Cover Common Terminology Work Group 

(Department of the Interior, 1985). 

I 

Ecosystem Geoposition 

I 

Mo--phology 

Barren land: A surface composed of expo <'P,d bare rock, 

other earthen material, or ice witt little or no 

vegetation. 

Built-up land: Structures and areas associa~,~ with intensive land use. This subview is furth~r divided into 

network, structure, and complex. 

Network-- An interconnected set of constructions used 

for transportation or communication. 

Structure--A construction having a uniq·~e form. 

Definition of DLG,E Features 11 
Complex--Cover of intensive use with much of the land 

covered by constructions. 

Agricultural. A group of associated structures 

functioning as a unit used predominantly for the 

production of food and fiber, such as livestock 

holding areas, fish hatcheries, and other developed 

land. 

Commercial. A group of associated structures functioning as a unit used predominantly for wholesale 

and (or) retail sale of goods and services. 

Entertainment/Recreational/Memorial. An area or 

group of associated structures functioning as a unit 

used predominantly (1) for leisure activities, ~2) for 

athletic or artistic events, (3) as archaeologtcal or 

historic sites, or ( 4) for burial of the dead. 

Disposal. A designated area where refuse is dumped 

or exists. 

Extraction. An excavation or a group of excavations 

or drillings in the Earth for the purpose of removing 

earth materials. 

High density building area. A congested, built-up 

area where all buildings cannot be represented on 

the map because of map scale. 

Industrial. A group of associated structures functioning as a unit used predominantly for manufacturing, testing, processing, or storage. 

Institutional. A group of associated structures 

functioning as a unit used predominantly for educational, correctional, governmental, medical, or 

religious purposes. 

Residential. A collection of structures used for 

human habitation. 

Transition. Area in change from one land use 

activity to another and characterized by a lack of 

information to predict future use or discern past use. 

Transportation. An area or group of structures that 

function as a unit associated with travel or conveyance of people and (or) goods, together with the 

necessary adjacent facilities. 

Utility. An area or group of structures that function 

as a unit to provide a public service and are used 

for the generation and (or) transportation of communications, water, gas, oil, or electricity. 

12 An Enhanced Digital Line Graph Design 

Cultivated cropland: Areas characterized by f'"'nction that 

are tilled and dominated by vegetation growth for 

the production of food and (or) fib_er. Cultivated 

cropland includes fallow land, land m a~y stage of 

annual crop production, and land being regularly cultivated for production of crops from perennial plants. 

Vegetation: An area that is extensively covered with plant 

life. 

Grassland--An extensive noncultivated area where 

vegetation is dominated by grasses o:-- grass-like 

plants. 

Shrubland--Areas covered with low-growing or stunted 

perennial vegetation, such as cactus, mesquite, or 

sagebrush, common to arid regions and usually not 

mixed with trees. 

Forestland--Areas on which vegetation is dominated 

by woody perennial plants having a sin~le, usually 

elongated main stem and generally few or no 

branches on its lower part. 

Water: Cover composed of flowing or staiJ~ing water, 

impounded or naturally occurring, wi~ channels or 

basins that are largely naturally occurnrrr. 

Division 

This view includes the cultural demarca+jons of the 

Earth's water and land surfaces. Two types of features 

exist in this view: areal divisions and boundaries. Boundaries may either delimit the areal divisions or, for his~orical reasons, occur as independent features. The subvtews 

of the division view are defined as follows: 

Administrative: A division under the jurisctiction of a 

common group for purposes such as pre"'ervation or 

exploitation of cultural or natural resources. 

Boundary: Part or all of a bounding or separrting line on 

the Earth's surface having current or past significance. 

Census: Divisions of the Earth's surface established by 

the Bureau of the Census for enum~rating and 

reporting the population of the United ftates. 

Hydrologic unit: Divisions of the Earth ~s sr~ace established by the U.S. Geological Survey based on 

properties, distribution, and circulation of water. 

Land parcel: Divisions of the Earth's surface based upon 

land ownership. 
Locale: A named place not otherwise categorized. 

Maritime: Divisions of the Earth's water surface identified for the purpose of navigation or control of ship 

traffic. 

Political: Divisions of the Earth's surface based upon 

governmental jurisdiction and activities such as 

voting and taxation. 

Survey system: Divisions of the Earth's surface to 

determine and delineate the form, extent, and 

position of land tracts by taking linear and angular 

measurements. 

Ecosystem 

Ecosystem is a view based on climate, vegetation, 

soils, and other controlling environmental factors that result 

in unique entities. These entities are often of large extent 

and mapped as land use/land cover classes or as named 

places. Tundra, desert, and wetland are included in this 

view. 

Geoposition 

Geoposition contains features associated with the 

measurement of the size and shape of the Earth. The view 

reflects points or lines on the Earth or its representation 

for which the location, relative to a particular datum, is 

well known. 

Morphology 

Morphology is a view based on the form of the land 

surface. A domain of features has been developed that 

reflects morphology as presented on Survey map products. 

Although morphologic features appear on map graphics 

through hypsography, within the scale limitations of the 

products, only those features that are named, labeled, or 

otherwise symbolized as unique entities appear in the 

feature list. While these features may require interpretation of boundary limits, the text and symbol information distinguish them. 

Attempts were made to organize morphologic 

features according to classical geomorphological treatments 

including processes such as erosion and deposition and 

generating agents such as glaciers, streams, wind, or 

volcanoes. While these approaches yield consistent 

features and correlate directly with geomorphological 

theory and practice, the infonnation required to make these 

types of feature distinctions is not available on map source 

materials without significant effort in the interpretation of 

hypsography. The level of knowledge necessary to 

perform this interpretation requires a skilled goomorphologist. Therefore an alternate approach was taken 

whereby the morphology of the land surface was organized 

directly into a domain of features that can be readily 

obtained from map graphics. The feature list reflects the 

named and symbolized entities organized and grouped to 

account for aliases such as cliff and bluff, or valley and 

hollow. 

Examples of Feature Objects 

This section provides examples of feature objects 

used to represent entities. The feature object represents the 

nonlocational aspect of the entity. To complete the 

representation of the entity, the feature ob.~,~.ct would be 

related to the spatial objects that represent tl1 ~ position and 

extent of the entity. 

Building 

Feature: Building 

Angle of orientation: 45 • 

Text: Not applicable 

Name: Not applicable 

Operational status: Operational 

Feature: Building 

Angle of orientation: Not applicable 

Text: Church 

Name: Not applicable 

Operational status: Operational 

Feature: Building 

Square, 4";0 angle, black interior 

Angle of orientation: Not applicable~ 

Text: Not applicable 

Name: The White House 

Operational status: Operational THE 

WHITEHOUSE 

Each of the feature objects would be related to the 

spatial objects (points, nodes, chains, or polygons as 

appropriate) to complete the description of the feature. 

Complex 

Feature: Institutional site 

Institutional function: Education 

Name: Smithsonian Institution 

.... Smithsonian 

Institution 

1+1 

a .o,..~ 

Definition of DLG·E Features 13 
In addition to this feature object, the individual 

buildings would be encoded as building feature objects 

("Building"). The feature object representing the 

Smithsonian Institution would be related to spatial objects 

(representing the grounds of the feature) and (or) other 

component features (representing the buildings or other 

component structures) to complete the description of the 

feature. 

Road 

Feature: Road 

Access restrictions: None 

Flow direction: Bidirectional 

Median category: Without median 

Name: Pletcher Road 

Number of lanes or tracks: Unspecified 

Operational status: Operational 

Road class: 2nd 

Road type: General case 

Route designator: Not applicable 

Width: Unspecified 

The individual instances of the road feature are 

shown in the illustration. One feature object (feature, 

attribute, and attribute value set) is required for each 

feature instance. 

REPRESENTATION OF FEATURES 

By using the components of the DLG-E data model, 

it is possible to create a number of different configurations 

of objects, attributes, and relationships to describe the 

members of the domain of defined features. Therefore, 

rules must be established for the representation of feature 

instances. Representation rules for feature instances may 

be based on spatial (that is, locational attributes and 

topological relationships) and (or) nonspatial aspects of the 

data. There are two types of feature instances: a basic 

feature instance and a compound feature instance. The 

basic feature instance consists of a feature object that is 

"composed or' a set of spatial objects (nodes, points, 

chains, or polygons). A compound feature instance 

consists of a feature object that is "composed or' basic 

feature instances and (or) other compound feature instances. For example, a named road such as "Lee Highway" 

is a compound feature consisting of a set of basic features 

corresponding to the segments of the road. 

14 An Enhanced Digital Line Graph Design 

In many cases, the feature instances are easily 

defined. For example, the feature instance of the feature 

"well" is a feature object "composed or• a single point 

representing the "well" location. Areal entities that are 

well-defined homogeneous regions, such as a p f1nd without 

islands, are also easily represented with a single area 

corresponding to each instance. However, ent~ties such as 

linear network systems present more difficulties in defining feature instances. 

A drainage network, for example, as shown on a 

map may consist of single- and double-line streams with 

islands and may be crossed by road, railroad, and other 

features. Determination of feature instances for this case 

must account for the intersection of single- and doubleline streams, direction of flow of the water, and intersections with the other features. Changes in 11 f1nlocational 

attributes, such as a name, also influence tl~ extent of 

these instances. 

For the purpose of creating the National Digital 

Cartographic Data Base from existing maps, a set of rules 

for the representation of feature instances should allow the 

basic features to be constructed directly frc m the map 

graphics. Aggregation of the basic feature instances to 

compound feature instances requires a corr bination of 

spatial and nonspatial rules. The delineatior and representation rules should provide basic feature ir~tances that 

are useful for aggregating into compound feat'lfe objects. 

The preparation of a set of representathn rules for 

feature instances is critical to the use of th~ domain of 

features. Although a domain of features has been developed, a variety of representations is possiHe for each 

instance of that feature. The work to arrive at a single 

consistent set of feature instance representaf'>n rules to 

complete the design of DLG-E is continuing. 

Feature Delineation Strategies 

A set of feature instance representation rules could 

be developed using a variety of criteria. A number of 

alternatives are discussed in this section. The specific set 

of rules chosen for the implementation of the DLG-E data 

model is described in "Rules for Feature Inst'Ttces." 

Representation rules describe what objects are used 

to represent a feature instance. Delimiting rules define 

where any given feature instance starts and s•'lps. These 

rules can be developed on the basis of spatial characteristics (locational attributes and topological mlationships), 

nonlocational attributes, nontopological relatiC'"lShips, or a 

combination of these. 

One method is for feature instances to c.orrespond to 

topological elements within the line graph repra.sentation of 

the features. This rule works well for entities represented 

as point and line objects. Areal features such as 

double-line streams present problems because of 
intersecting single-line streams. Treating the entire area, 

that is, the topological elemental area, as a feature instance fails to retain critical information about direction of 

flow of water from the single-line streams into the 

double-line representation. Also, in a composite data base, 

this rule results in features in one category; for example, 

roads, delineated by intersection of features from the same 

or any other category. Thus, a road feature instance may 

be delineated by the intersection of a stream with the road 

on one end and the intersection of a contour line with the 

road on the opposite end. If the composite data base is 

structured as a single graph, all topological element 

intersections become delimiters of feature instances. 

To avoid these problems, the rule can be changed so 

that feature instances are bounded by only "like" features; 

for example, a stream feature instance begins at the 

intersection with another stream and continues until a 

second intersection with a third stream occurs. Termination of the coordinate representation of an entity is also a 

bounding criteria. Essentially, road feature instances would 

only be bounded by road intersections, not by road/contour 

intersections and so forth. A problem with this rule is that 

changes in nonspatial attributes do not yield separate 

feature instances. For example, a two-lane road changing 

to a four-lane would all be part of the same feature 

instance and the two- and four-lane attributes must be 

attached to a single feature instance. Under this rule, are 

single- and double-line streams like features? One could 

impose a subrule that states that like features must be of 

the same dimensionality. The term "like" must be rigorously defined for this rule to be effective. 

An alternate strategy is to delineate feature instances 

based solely on their nonspatial attributes. A new feature 

instance would occur only with a change in nonspatial 

attribution. For example, a road changing from four lanes 

to six lanes would dictate a new feature instance, but a 

road intersecting another road would not. A problem with 

this rule is that all roads with the same value for the 

attribute "road class," regardless of location, are a part of 

the same feature instance. A requirement of continuity 

partly solves this; however, roads that intersect and retain 

the same nonspatial attributes would still form the same 

feature instance. 

The most useful representation of feature instances 

requires both spatial and nonspatial rules to be used 

together. The optimum combination of these rules will 

vary with the entity under consideration, but one or more 

rules must be used to specify unique feature instances for 

the Geological Survey. 

Rules for Feature Instances 

DLG-E uses a combination of spatial and nonspatial 

rules to represent feature instances. The sections below 

list a general set of rules that have been developed for 

determining feature instances in the DLG-E data model. 

These general rules are augmented by featur~~ specific rules, 

examples of which are given in appendix P. 

Basic Features 

All objects that are part of a basic feature instance 

must be contiguous, uniform in dimensionality, and 

homogeneous in attribution. The featurr. instances are 

bounded by the intersection with a like feature. 

Ground features having linear extent are represented 

by basic feature instances composed of a set of chains that 

are homogeneous in orientation and contigu'lus (that is, the 

chain sets are both ordered and directed). A linear basic 

feature instance has one starting point and O"le ending point 

and shall not contain any network type branches. 

All features having areal extents ar~ composed of 

the spatial object "polygon." Objects in the "composed 

of' relation will be unordered. 

A defined subset of features having a':'eal extent will, 

in addition to the "composed of' relation, cr~ a "bounded 

by" relation. The "bounded by" relation holds an ordered 

set of chains that define the boundary of tl"~ areal feature. 

The following features carry the "bounded by" relation: 

All features in the Divisions/Adminiftrative subview 

All features in the Divisions/Political subview 

All areal features in the Divisions/Swvey Systems subview 

Selected features in the Cover/Water subview 

Features having areal extent but indeterminate 

boundaries will be spatially represented b:' an unordered 

set of topological polygons using the "corrl')()sed of'' relation. Nonfeature chains will be used where necessary to 

arbitrarily close off the extent of the areal feature. Ties to 

structures inside a complex (buildings in a university, for 

example) will not be directly represented. 

Named Features 

Features having a proper name may be represented 

by either the basic or compound type of feature. If the 

feature can be represented as a single basic feature instance, the name is stored as an attribute c11 that instance. 

If, however, the feature must be represented as a compound feature, the name is stored as an attribute on the 

higher level compound feature. Since a single name may 

apply to a number of different features at the basic level, 

the entity label of the higher level named feature need not 

match the constituent basic feature instances. Most often, 

the feature "Named Feature" will be used. Currently, theonly attribute that may cause basic features to be linked to -

a higher level feature due to equivalence of the value 

assigned to that attribute is the "name" attibute. 

Representatior of Features 15 
Modeling Constructs 

Most aspects of geographic reality are readily 

described using the feature objects derived from the five 

views, spatial objects, topological relationships, and the 

"composed of' and "bounded by" relationships. However, 

to model certain conditions some additional features, 

attributes, and relationships are required. [Note: The 

additional features referred to in this section are not listed 

in appendix A.] The use of these in modeling certain 

phenomena is discussed in the following sections. 

Modeling of Network Flows 

Flow and connectivity of linear features are encoded 

through the direction of the chains and by relationships 

between chains and nodes. Flow is represented as a 

nonspatial attribute on the feature instance as shown below. 

Attribute: Directional status 

Alternating 

Bidirectional 

Not applicable 

One way 

Unknown 

Unspecified 

This attribute indicates if the flow moves in both directions 

along the instance ("bidirectional"), alternates in direction 

along the flow (

11 altemating"), or moves one way along the 

instance. 

Connectivity between linear and areal features is 

encoded using the nodes common to the chains that are 

part of the linear feature and the edge of the areal feature. 

Flow between areal features is encoded using the feature 

"junction" (the occurrence of an intersection of two areal 

features having flow) and the relationships "connected to" 

or "inflow from/outflow to." These relationships are 

attached to the areal features and link the features to the 

junctions where they meet other features. Sometimes in 

the map of hydrographic features, gaps will occur in the 

flow network (such as between the shoreline of a reservoir 

behind an earthen dam and the stream flowing from the 

reservoir). To model this situation the feature "connector" 

is used with the relationships "inflow from/outflow to." If 

the location of the "connector" is unknown, the connector 

feature object will not be composed of any spatial objects. 

Vertical Feature Relationships 

Use of attributes 

The attribute "relationship to surface" is used with 

various feature instances to indicate the vertical location of 

16 An Enhanced Digital Line Graph Design 

a feature relative to the surface of the domair in potentially ambiguous situations. The attribute has th~ following 

attribute values: 

Attribute: Relationship to surface 

Awash at water surface 

Elevated or suspended above 

surface 

Exposed at surface 

Submerged below water surface 

Under land surface 

In general, the features of the cover and ecosystem 

view are considered to be on the surface in land areas and 

to be exposed at the water surface in water areas. Exceptions include features normally considered devated or 

suspended above surface, such as: 

Bridge 

Cableway 

Conveyor 

Transmission line 

and features normally considered under the la"'q surface, 

such as: 

Pipeline 

Tunnel 

Selected features in the cover view (aqueduct, 

canal/ditch, railway, pipeline, road, road i,..terchange, 

stream/river, and trail features) that coincide with a bridge 

or tunnel feature are considered to be on/in th ~ bridge or 

tunnel. These coincident features are artomatically 

considered to be "elevated or suspended above surface" or 

"under land surface" where they coincide with the bridge 

or tunnel. The "relationship to surface" attri'·r1te is not 

applied in these cases. Features that have instances where 

the relationship to the surface is other than th~ conditions 

described will carry the "relationship to surface" attribute. 

The features in the motphology view c1~scribe the 

form of the surface. They are exposed at the lr'ld surface. 

In cases where they are coincident with wat;;r features, 

they are considered to be submerged below the water 

surface. In one ambiguous case, a rock (repre:~~nted by a 

point) may be exposed, awash, or submerged. The rock 

feature carries the "relationship to surface" attribute. 

Similar to morphology, features in the geoposition 

view are measurements of the surface, and o ".Cur at the 

surface. Because spot elevations and control stations are 
occasionally located on elevated or suspended structures, 

this feature carries the "relationship to surface" attribute. 

Use of "underpass" 

Where it is necessary to preserve a vertical relationship between two feature instances, the feature "underpass" 

shall be utilized. This feature is employed where the 

relative vertical information between the features cannot be 

determined by other information. It is normally used 

where features carrying traffic or having flow (such as 

aqueduct, canal, railway, road, and stream) pass under 

other features. 

It is not used where the relative vertical relationship 

between features can be determined from other information, 

such as knowledge of one feature being underground or 

elevated while the second feature is on the surface. For 

example, it would not be used where a road coincident 

with a bridge passes over another (not coincident) road, or 

where a road coincident with a tunnel passes under a 

railroad. 

The dimensionality of an instance of an underpass 

shall depend on the dimensionality of the overpassing/ 

underpassing features, according to the following table. 

Table 5. Dimensionality of "underpass" instance from 

intersection of features 

Dimension of feature 1 

Dimension of feature 2 

! 

~ 

! ~ 

0 

1 

1 

2 

Only two features may be vertically related with the 

"underpass" feature. In the case of three or more features 

overpassing each other at the same spatial location, only 

vertically adjacent features shall be referenced in the 

underpass feature. Thus, a triple overpass shall generate 

two underpass instances: one for the top and middle features and one for the middle and bottom features. 

Spatial Extent 

The feature "domain" is used to define the spatial 

extent of the data set It includes the area of the Earth 

covered by the data set being transferred. It excludes the 

area outside the domain and any void or holiday areas 

occurring within the area. Features represented by points 

and (or) chains (or portions thereof) that coincide with the 

edge of domain appear in both data sets that adjoin that 

edge. Features represented by areas, of which only the 

boundary is coincident with the edge of d1main, appear 

only in the data set that contains the areal r.xtent. 

Using the Model to Represent Cartographic 

Features 

Rules for bounding feature instancef:, composition 

rules for representing feature instances, rules. for ag~egating feature instances, and rules for moieling vanous 

situations have been discussed in this section. Different 

sets of rules for representing a feature may be useful in 

different applications of that feature. By varyin~ these 

rules for creating instances of the features.' a vanety of 

implementations are possible using the elements and 

structure provided by the model. 

However, for any given implementation, specific 

rules must be created and observed to definr. the representation of feature instances. A prototype sr.t of rules for 

use with the set of features contained in the example data 

set is given in appendix B. 

DATA MODEL IMPLEMENTATION 

Previous sections have defined the DLG-E data 

reality, that is, the scope of the data that is of interest in 

this application, and the DLG-E data mod::l, the sets of 

components and relationships that are used to describe the 

elements of the data reality. However, to ercode, transfer, 

or use the data, the logical organization of the components 

and the component relationships of the DLG-E data model 

must be explicitly defined. This definitic n is done by 

creating a specific data structure. A data st'llcture can, in 

turn, be translated into a specific file structure by a set of 

rules that specify the logical implementation of. the data 

structure within a given computing system envrronment. 

Many different data structures and file strr~tures can be 

generated from one data model. 

Two implementations of the DLG-E data model are 

considered. The first implementation of the model uses 

the existing DLG-0 file structure (USGS, 19~7a) and adds 

modules to hold the DLG-E elements. This new file 

structure is called DLG-0+. The "DLG-0" part holds the 

spatial objects, locational attributes, an-i topological 

relationships. The "+" part adds a series cf files to hold 

the DLG-E features, nonlocational attributes, and nontopological relationships. Details on this implemen~tion 

are given in appendix B. The example data set descnbed 

in appendix B is implemented in the DLG-0+ data 

structure. 

The second implementation uses the framework of 

the Spatial Data Transfer Specification (SL"TS) described 

in "The Proposed Standard for Digital Cartographic Data" 

(Digital Cartographic Data Standards Task Force, 1988). 

This framework has a strictly defined and o .. ganized set of 

modules, fields, and subfields that are usr-d to hold the 

Data Model lmp'~mentatlon 17 
various components of the DLG-E data model. The 

details on implementing the DLG-E model in SDTS are 

given in appendix C. 

SUMMARY AND FUTURE RESEARCH 

Summary 

In the DLG-E model, the phenomena of geographic 

and cartographic data are considered, in totality, as entities. 

Entities are individual phenomena in the real world. A 

feature is an abstraction of a set of entities, defined by a 

selected set of common attributes and relationships that are 

properties of the corresponding entities. Features represent 

the sum of our interpretations of phenomena on or near the 

Earth's surface. Buildings, bridges, roads, streams, 

grassland, and counties are examples of features. The 

components of the digital representation of a feature 

instance are termed objects. Cartographic data may be 

considered to be composed of objects, attributes, and 

relationships. 

Objects are the basic units of representation of the 

encoded phenomenon. Attributes are the locational and 

nonlocational properties of the entities represented by the 

objects. Relationships are the topological and nontopological links between the objects. The objects in the DLG-E 

model are of two types, feature objects and spatial objects. 

Nonlocational attributes and non topological relationships are 

associated with feature objects. Locational attributes and 

topological relationships are associated with spatial objects. 

Four spatial objects are defined: points, nodes, chains, and 

polygons. A given feature object has relationships with 

other feature objects and (or) spatial objects. Taken 

collectively, these objects, attributes, and relationships 

constitute the DLG-E data model. These concepts are 

developed in "Concepts of the DLG-E Design." 

To establish the domain of features for DLG-E, an 

approach using a set of classes, or views, of geographic 

entities was adopted. The views are exclusive; each view 

is a self-contained analytical approach to the entire range 

of world features. Because each view is independent of 

the others, a single point on the surface of the Earth can 

be represented under multiple views. The five views that 

were developed are cover, division, ecosystem, geoposition, 

and morphology. "Definition of DLG-E Features" describes the methodology used in creating the DLG-E features, and the domain of DLG-E features is enumerated in 

appendix A. 

By using the DLG-E data model, a wide variety of 

representations of features could be formulated from the 

domain of defined features. Therefore, rules must be 

established for the representation of occurrences of the 

features or "feature instances." Representation rules for 

18 An Enhanced Digital Line Graph Design 

feature instances may be based on spatial and (or) nonspatial attributes of the data. A prototype set of rules for 

the representation of feature instances wa<- created. 

Combining selected basic feature instances into compound 

feature instances uses a combination of spatia' and nonspatial rules. Representation rules are discussed in 

"Representation of Features." An example DLG-E data set 

and the set of rules used to create it are provided in 

appendix B. 

A specific data structure explicitly defmes the logical 

organization of the components and the component relationships of the DLG-E data model. A data structure can, 

in turn, be translated into a file structure by a set of rules 

that specify the logical implementation of the da .. a structure 

within a given computing system environment. Many different data structures and file structures can br. generated 

from one data model. Two implementations of the DLG-E 

data model are discussed in "Data Model Implementation," 

and appendixes B and C provide the respective guidelines 

for implementing the DLG-E data model in the DLG-0+ 

data structure and in SDTS. 

Future Research 

The preparation of a set of representatic n rules for 

all feature instances is critical to the use of the domain of 

features. Although a domain of features has been developed, a variety of representations are possib'e for each 

instance of that feature. The work to arrive at a single, 

consistent set of feature instance representation rules to 

complete the design of DLG-E is continuing. 

Further work on the implementation of the DLG-E 

data model in a variety of computer environments needs to 

be performed. One implementation of the mo1el will be 

within the context of relational and (or) object-oriented 

data base systems. Research on this topic will be pursued. 

Finally, a series of system developmer~ activities 

required to implement prototype DLG-E prodnction must 

be undertaken. These activities include further refinement 

of feature, attribute, and attribute value definitio"ls; creation 

of extraction and product rule sets; establ:~hment of 

procedures and software for data collection and conversion 

of existing data sets; and further testing of implementations of the DLG-0+ and SDTS data stru~tures with 

more extensive data sets. 

Of course, these activities may point ont areas not 

adequately addressed by the model. Therefore, modifications and improvements to the model may occ'll'. 

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APPENDIXES 

APPENDIX A 

DLG-E FEATURES 

Section 

1. An introduction to the DLG-E domain A-1 

2. Summary of DLG-E domain and feature count A-4 

3. Features of the DLG-E domain listed by view A-5 

4. Alphabetic list of features A-10 

5. DLG-E feature domain A-12 

6. Alphabetic list of DLG-E attributes 

and associated attribute values A-51 

7. Alphabetic list of DLG-E 

attributes of attribute values A-64 

APPENDIX A 

DLG-E FEATURES 

1. AN INTRODUCTION TO THE DLG-E DOMAIN 

This appendix details the contents of the DLG-E domain. The content of this domain is not all-inclusive and does not 

attempt to defme all the entities in the real world. This domain was established to define a set of features that are found 

on U.S. Geological Survey National Mapping Division (NMD) source materials and reflect the requirements of the NMD. 

The DLG-E domain is organized as follows: 

View: Subview 1: Subview 2: Subview 3: 

Feature: Feature Definition 

Attribute 

Attribute Values-------> Attribute of Attribute Value 

Attribute Values 

A description of each of these concepts follows. 

VIEW 

The DLG-E domain was developed by using an approach that incorporates a concept of world views of spatial entities. 

The concept of multiple views of the world and a hierarchy of subviews within each world view was used to define a 

domain of features found on NMD products. The views should not be confused with data collection categories. Neither 

the views nor the subview hierarchy will be stored with the feature data. Categories may be chosen, if so desired, to 

group features during data collection. 

A world view is defined as a systematic classification of a set of real world phenomena in which all members of the set. 

possess a common defming characteristic. The defining characteristic is specified explicitly in the definition of each 

view. Five world views were developed and documented to reflect the source material and requirements of the NMD. 

The views along with their definitions and a brief explanation are as follows: 

Cover: 

Division: 

Ecosystem: 

Geoposition: 

Morphology: 

This world view reflects physical or material features at a location on or near the surface of the Bartl·. 

While this view is strictly based on form, at the lowest level features may be differentiated by 

function. 

Most of the features in the domain are contained in this view (122 out of 202). Due to the diversity 

in the features defined by this view, additional subviews were added. These subviews clarify the 

distinctions between features in the view. 

This world view reflects cultural demarcations of the Earth's surface for a particular purpose or 

separations resulting from human activity. 

This view includes the cultural demarcations of the Earth's water and land surfaces. Two types of 

features exist in this view: areal divisions and boundaries. Boundaries may either delimit the areal 

divisions or occur as independent features. 

This world view is based on the climate, vegetation, soils, and other controlling environmental facton· 

that result in unique ecological units. 

The entities in this view are often of large extent and are mapped as land use/land cover classes or r~ 

named places. Tundra, desert, and wetland are the features included in this view. 

This world view reflects measurement data about the Earth's surface and contains points or lines on 

the Earth or its representation for which location, relative to a particular datum, is well known. 

Several of the features in this view, such as contours and spot elevations, exist only on maps even 

though they represent real world phenomena. 

This world view is based on the form of the land. While a strict geomorphological interpretation of 

landforms based on process is inherent in the contour information on USGS maps, the actual features 
must be interpreted. However, some of these features carry names and those features must be coded 

in the digital data. Thus, morphological features are those landform features that are named, labeled, 

or symbolized as distinct entities on current NMD products. 

Attempts were made to organize morphologic features according to classical geomorphological 

treatments, including processes such as erosion and deposition and generating agents such as glaciers, 

stream, wind, or volcanoes. While these approaches yield consistent features and correlate directly 

with geomorphological theory and practice, the information required to make these types of feature 

distinctions is not available on NMD source materials without significant interpretation of hypsography. 

The level of knowledge necessary to perform this interpretation requires a skilled geomor'"'lhologist. 

Thus, the morphology of the land surface was organized directly into a domain of featur~~ that can be 

readily obtained from NMD graphics. The feature list reflects the named and symbolizee entities 

organized and grouped to account for aliases such as cliff and bluff, valley and hollow, ~tc. 

This world view approach for specifying features was designed to be flexible and expandable by providing the capability 

to appropriately fit unclassified entities into the schema. It also provides a framework for comparison to other sets of 

features as defined by other organizations. Other organizations may have requirements for different views, subviews, or 

augmenting the features within the existing five views. 

FEATURE 

The DLG-E model defines the concept of feature as a class of phenomena with common attributes and rela'ionships 

encompassing both real world entities along with their digital (object) representation. 

Feature 

I _____ I ____ _ 

I 

Entity 

"Real World" 

I 

Object 

''Representation'' 

Only features found on NMD source material and reflecting NMD requirements are included in the domain. Features 

along with their definitions are listed alphabetically under each view or subview 1, 2, or 3 headings. Several indexes are 

provided in this appendix to help locate any feature. 

ATIRIBUTE 

Attributes are the locational or nonlocational characteristics of a feature or of an attribute value. Locational characteristics 

of a feature describe the geographic location or geometric dimension, while nonlocational characteristics include such 

concepts as operational status, name, and product. All attributes that are listed in the DLG-E domain for a feature must 

be populated with at least one attribute value. A list of all attributes with their associated attribute values ~xisting in the 

DLG-E domain can be found in section 6 of this appendix. No definitions are included for the attributes a"'ld attribute 

values in this domain; an effort to complete this work is ongoing. 

In the domain, all attributes along with their associated attribute values are listed for each feature. For example, the 

feature "Pipeline" has the following attributes: 

Name 

Operational status 

Product 

Relationship to surface 

Other attributes such as "length" or "width" may be associated with the feature "pipeline"; however, they ar~ not included 

in the DLG-E domain because they are not requirements of the Geological Survey. 

ATTRIBUTE VALUE 

Attribute values are measurements assigned to an attribute for a given feature occurrence or for another attribute value. 

At least one attribute value must be assigned to every attribute listed for a feature. Several of the attribute values that 

are frequently used in the DLG-E domain are described below. 

A-2 An Enhanced Digital Line Graph Design 
Not Applicable, Unspecified, Unknown 

These special attribute values are available for selected attributes and should be used as follows: 

Not applicable: 

Unspecified: 

Unknown: 

Used when there is no relevant value for a particular attribute. 

Used when there is a possible value for an attribute but no value is provided. 

Used when a value should be provided but for some reason the information is not availabh. 

In general, values of unknown will be resolved prior to the release of the data. 

General Case 

The attribute value "general case" is used when the common usage of an attribute is required. For example, "railway 

category" is an attribute of the feature "railway," with values of "general case," "inclined railway," "logging," "rapid 

transit," and "unknown." The options "inclined railway," "logging," and "rapid transit" are special cases of railways th:~t 

occur infrequently. Since the DLG-E model specifies that at least one attribute value must be chosen for each attribut~, 

a general purpose railway would be coded as "general case." 

ATTRIBUTE OF ATTRIBUTE VALUE 

An attribute of an attribute value is a valid construct in the DLG-E model. The feature "well" will be used to illustra .. ~ 

this concept. A portion of the entry for "well" from the DLG-E domain is reproduced below. 

Well 

Product 

Gas 

Heat 

Oil 

A pit or hole dug or bored into the Earth for the 

extraction of oil, water, other fluids, or gases. 

Water------------> Flow Characteristics 

Unspecified Flowing 

Unknown Not flowing 

Hydrographic Category 

Dry 

Not applicable 

Perennial 

Water Characteristics 

Alkaline 

Hot 

Mineral 

Salt 

Unspecified 

The attributes "flow characteristics," "hydrographic category," and "water characteristics" are attributes of the attribute 

value "water" under the attribute "product." This is modeled in this way because these three attributes are pertinent o:1ly 

when the value "water" is chosen from the attribute "product." These three attributes are not relevant for oil wells or 

natural gas wells but apply to water wells only, and therefore are associated as attributes of the attribute value "water" 

under the "product" attribute. 

''Text" is a common attribute of an attribute value. The attribute "text" is used when a description for an attribute va1

ue 

is needed. For example, "text" is an attribute of the attribute value "sports site type" for the feature "sports site." If a 

municipal golf course must be collected, "golf course" is chosen as a value, and the "text" attribute would be used to 

hold the text "municipal." Any type of descriptive text may be included in the "text" field. This field is not to be u~~.d 

to record proper names. 

Appendix A-3 
Appendix A 

Page 

13 

13 

13 

13 

17 

28 

28 

28 

28 

30 

30 

31 

31 

32 

32 

33 

33 

34 

35 

35 

35 

35 

36 

36 

39 

39 

39 

40 

40 

41 

41 

41 

42 

43 

45 

45 

47 

2. SUMMARY OF DLG-E DOMAIN AND FEATURE COUNT 

Subview 1 Subview 2 Subview 3 

Number 

Of'Feaiiires 

Cover ................................................... 122 

Barren land . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

Built-up land . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 

Network ......................... 28 

Structure . . . . . . . . . . . . . . . . . . . . . . . . . 54 

Complex ......................... 37 

Agricultural . . . . . . . . . . . . 3 

Commercial . . . . . . . . . . . . 1 

Entertainment/ 

Recreational/ 

Memorial ............. 8 

Disposal . . . . . . . . . . . . . . 2 

Extraction . . . . . . . . . . . . . 2 

High density 

building area . . . . . . . . . . . 1 

Industrial . . . . . . . . . . . . . . 4 

Institutional . . . . . . . . . . . . 1 

Residential . . . . . . . . . . . . . 1 

Transition . . . . . . . . . . . . . 1 

Transportation . . . . . . . . . . . 8 

Utility . . . . . . . . . . . . . . . . 5 

Cultivated cropland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Grassland . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Shrubland . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Forestland . . . . . . . . . . . . . . . . . . . . . . . . . 3 

Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

Division . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 

Administrative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Boundary ...................................... 4 

Census ....................................... 5 

Hydrologic unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Land parcel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Locale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Maritime ...................................... 4 

Political . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

Survey system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

Geoposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Morphology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 

Total .................................................... 202 

A·4 An Enhanced Digital Line Graph Design 
Cover 

3. FEATURES OF THE DLG-E DOMAIN LISTED BY VIEW 

Subview 1 

Barren land 

Barren land 

Firebreak 

Ice mass 

Mud pot 

Built-up land 

Subview 2 

Network 

Aqueduct 

Canal/Ditch 

Cul de sac 

Pipeline 

Railway 

Road 

Trail 

Transmission line 

Structures 

Apron 

Athletic field 

Beacon 

Boardwalk 

Breakwater/Jetty 

Bridge 

Building 

Cableway 

Chimney 

Cliff dwelling 

Conveyor 

Dam/Weir 

Dish 

Draw span 

Drilling platfonn 

Drive-in theater screen 

Drydock 

Fish ladder 

Flume 

Gaging station 

Gate 

Grave 

Helipad 

Historical marker 

Kiln 

Launch pad 

Launching ramp 

Lock 

Masomy shore 

Mine entrance 

Penstock 

Pier/Wharf 

Point monument 

Post 

Prospect 

Pump 

Racetrack 

Recreational slide 

Reservoir 

Runway 

Siphon 

Ski jump 

Spillway 

Tank 

Subview 3 

Appendix A-5 
Subview 1 

Cover Built-up land 

A-6 An Enhanced Digital line Graph Design 

Subview 2 

Structures (continued) 

Taxiway 

Tower 

Tunnel 

Tunnel entrance 

Turntable 

Wall 

Water intake/outflow 

Well 

Windmill 

Wreck 

Complex 

Subview 3 

Agri n.ultural 

Fish hatchery 

H0lding pen 

Mmne activity 

sfte 

Corrmercial 

Shopping center 

Entertainment/ 

Recreational/ 

Me"ll.orial 

Archeological 

site/Ruins 

Crunpground 

c~metery 

EYhibition 

ground 

Mmna 

Outdoor theater 

Prrk 

Spxts site 

Disposal area 

DJ~sposal site 

Wrecking yard 

Extraction area 

M~ne 

Well field 

High density 

building area 

High density 

tuilding area 

Jnd\''l.trial 

In1ustrial site 

Mineral pile 

Proving ground 

Tank farm 

Inst:t.utional 

hlstitutional site 

Res~rlential 

Trailer park 

Transition area 

Transition area 

Transportation 

Aircraft facility 

Irterchange 

Launch facility 

Parking site 

Rail way yard 

Rest site 

Toll plaza 

Traffic 

inspection 

facility 
Cover 

Division 

Subview 1 

Built-up land 

Cultivated cropland 

Cultivated cropland 

Vegetation 

Water 

Area to be submerged 

Bay/Estuary/Inlet 

Ford 

Gut 

Inundation area 

Lake/Pond 

Rapids 

Sea/Ocean 

Shoreline 

Spring 

Stream/River 

Submerged stream 

Waterfall 

Administrative 

Reservation 

Boundary 

Boundary line 

Boundary point 

Fence line 

International date line 

Census 

Census block 

Census block group 

Census County Division (CCD)/ 

Minor Civil Division (MCD) 

Subview 2 

Complex (continued) 

Grassland 

Grassland 

Shrub land 

Shrub land 

Forestland 

Tree 

Trees 

Snag/Stump 

Census tract/Block Numbering Area (BNA) 

Metropolitan Statistical Area (MSA) 

Hydrologic unit 

Hydrologic unit 

Land parcel 

Land parcel 

Locale 

Locale 

Maritime 

Anchorage 

Hazard zone 

Lane 

Special use zone 

Political 

City 

County 

Exclusive Economic Zone (EEZ) 

Subview 3 

Utility 

Cable/Pipelir~ 

site 

Dam site 

Pipeline 

regulation 

station 

Power site 

Substation 

Appendix A-7 
Division 

Ecosystem 

Desert 

Tundra 

Wetland 

Geoposition 

Contour (bathymetric) 

Contour (land) 

Control station 

Mile marker 

Spot elevation 

Morphology 

Arch 

Bar 

Basin 

Beach 

Bend 

Cape 

Cave 

Cave entrance 

Cliff 

Crevasse 

Disturbed surface 

Dunes 

Embankment 

Fault 

Flat 

Foreshore 

Fumarole 

Gap 

Geyser 

Iceberg 

Iceberg tongue 

Incline/Flow 

Island 

Isthmus 

Moraine 

Mount 

Pinnacle 

Plain 

Range 

Reef 

Ridge 

Ridge line 

Rock 

Sastrugi 

Sink 

Summit 

Terrace 

Subview 1 

Political (continued) 

Minor civil unit 

Minor civil subunit 

Nation 

State/Territory 

Survey system 

Baseline 

Georgia Survey District 

Homestead entry 

Land grant 

Principal meridian 

Public survey area 

Survey corner 

Survey point 

A-8 An Enhanced Digital Line Graph Design 

Subview 2 Subview 3 
Morphology (continued) 

Trench 

Valley 

Wash 

Subview 1 Subview 2 Subview 3 

Appendix A·9 
4. ALPHABETIC LIST OF FEATURES 

Page 

Aircraft facility . . . . . . . . . . . . . . . . . 33 

Anchorage .................... 41 

Apron . . . . . . . . . . . . . . . . . . . . . . . 17 

Aqueduct . . . . . . . . . . . . . . . . . . . . . 13 

Arch ........................ 47 

Archeological site/Ruins . . . . . . . . . . . . 28 

Area to be submerged . . . . . . . . . . . . . 36 

Athletic field . . . . . . . . . . . . . . . . . . . 17 

Bar ......................... 47 

Barren land . . . . . . . . . . . . . . . . . . . . 13 

Baseline . . . . . . . . . . . . . . . . . . . . . . 43 

Basin ....................... 47 

Bay/Estuary/Inlet . . . . . . . . . . . . . . . . 36 

Beach ....................... 47 

Beacon . . . . . . . . . . . . . . . . . . . . . . 17 

Bend ........................ 47 

Boardwalk . . . . . . . . . . . . . . . . . . . . 18 

Boundary line . . . . . . . . . . . . . . . . . . 39 

Boundary point . . . . . . . . . . . . . . . . . 40 

Breakwater/Jetty . . . . . . . . . . . . . . . . . 18 

Bridge . . . . . . . . . . . . . . . . . . . . . . . 18 

Building . . . . . . . . . . . . . . . . . . . . . . 19 

Cable/Pipeline site . . . . . . . . . . . . . . . 34 

Cableway . . . . . . . . . . . . . . . . . . . . . 19 

Campground ................... 28 

Canal/Ditch . . . . . . . . . . . . . . . . . . . . 13 

Cape ........................ 47 

Cave ........................ 47 

Cave entrance . . . . . . . . . . . . . . . . . . 48 

Cemetery . . . . . . . . . . . . . . . . . . . . . 29 

Census block . . . . . . . . . . . . . . . . . . . 40 

Census block group . . . . . . . . . . . . . . 40 

Cen;-~s C?~~y Division/Minor 

C1vll DIVISion . . . . . . . . . . . . . . . . . 40 

Census tract/Block Numbering Area . . . . 40 

Chimney . . . . . . . . . . . . . . . . . . . . . 19 

City ........................ 42 

Cliff . . . . . . . . . . . . . . . . . . . . . . . . 48 

Cliff dwelling . . . . . . . . . . . . . . . . . . 19 

Contour (bathymetric) . . . . . . . . . . . . . 45 

Contour (land) . . . . . . . . . . . . . . . . . . 46 

Control station . . . . . . . . . . . . . . . . . . 46 

Conveyor . . . . . . . . . . . . . . . . . . . . . 20 

County ...................... 42 

Crevasse . . . . . . . . . . . . . . . . . . . . . 48 

Cul de sac . . . . . . . . . . . . . . . . . . . . 14 

Cultivated cropland . . . . . . . . . . . . . . . 35 

Dam site ..................... 34 

Dam/Weir . . . . . . . . . . . . . . . . . . . . . 20 

Desert ....................... 45 

Dish ........................ 20 

Disposal site . . . . . . . . . . . . . . . . . . . 30 

Disturbed surface . . . . . . . . . . . . . . . . 48 

Draw span . . . . . . . . . . . . . . . . . . . . 20 

Drilling platform . . . . . . . . . . . . . . . . 20 

Drive-in theater screen . . . . . . . . . . . . . 20 

Drydock ...................... 20 

Dunes ....................... 48 

Embankment . . . . . . . . . . . . . . . . . . . 48 

Exclusive Economic Zone . . . . . . . . . . 42 

Exhibition ground . . . . . . . . . . . . . . . . 29 

Fault ........................ 48 

Fence line . . . . . . . . . . . . . . . . . . . . 40 

A-10 An Enhanced Digital Line Graph Design 

Page 

Firebreak . . . . . . . . . . . . . . . . . . . . . 13 

Fish hatchery . . . . . . . . . . . . . . . . . . 28 

Fish ladder . . . . . . . . . . . . . . . . . . . . 21 

Flat ......................... 48 

Flume ....................... 21 

Ford ........................ 36 

Foreshore . . . . . . . . . . . . . . . . . . . . . 48 

Fumarole . . . . . . . . . . . . . . . . . . . . . 48 

Gagirlg station . . . . . . . . . . . . . . . . . . 21 

Gap ........................ 48 

Gate ........................ 21 

Georgia Survey District . . . . . . . . . . . . 43 

Geyser ....................... 49 

Grassland . . . . . . . . . . . . . . . . . . . . . 35 

Grave . . . . . . . . . . . . . . . . . . . . . . . 21 

Gut ......................... 36 

Hazard zone . . . . . . . . . . . . . . . . . . . 42 

Helipad ...................... 21 

High density building area . . . . . . . . . . 31 

Historical marker . . . . . . . . . . . . . . . . 22 

Holding pen . . . . . . . . . . . . . . . . . . . 28 

Homestead entry . . . . . . . . . . . . . . . . 43 

Hydrologic unit . . . . . . . . . . . . . . . . . 40 

Iceberg ...................... 49 

Iceberg tongue . . . . . . . . . . . . . . . . . . 49 

Ice mass . . . . . . . . . . . . . . . . . . . . . 13 

Incline/Flow . . . . . . . . . . . . . . . . . . . 49 

Industrial site . . . . . . . . . . . . . . . . . . 31 

Inundation area . . . . . . . . . . . . . . . . . 37 

Institutional site . . . . . . . . . . . . . . . . . 32 

Interchange . . . . . . . . . . . . . . . . . . . . 33 

International Date Line . . . . . . . . . . . . 40 

Island . . . . . . . . . . . . . . . . . . . . . . . 49 

Isthmus ...................... 49 

Kiln ........................ 22 

Lake/Pond .................... 37 

Land grant . . . . . . . . . . . . . . . . . . . . 44 

Land parcel . . . . . . . . . . . . . . . . . . . 41 

Lane ........................ 42 

Launch pad . . . . . . . . . . . . . . . . . . . . 22 

Launch facility . . . . . . . . . . . . . . . . . 33 

Launching ramp . . . . . . . . . . . . . . . . . 22 

Locale ....................... 41 

Lock ........................ 22 

Marina ....................... 29 

Marine activity site . . . . . . . . . . . . . . . 28 

Masonry shore . . . . . . . . . . . . . . . . . . 22 

Metropolitan Statistical Area (MSA) . . . . 40 

Mile marker . . . . . . . . . . . . . . . . . . . 46 

Mine ........................ 30 

Mine entrance .................. 22 

Mineral pile . . . . . . . . . . . . . . . . . . . 32 

Minor civil unit . . . . . . . . . . . . . . . . . 43 

Mirlor civil subunit . . . . . . . . . . . . . . . 43 

Moraine ...................... 49 

Mount ....................... 49 

Mud pot ..................... 13 

Nation ....................... 43 

Outdoor theater . . . . . . . . . . . . . . . . . 29 

Park ........................ 29 

Parkirlg site . . . . . . . . . . . . . . . . . . . 33 

Penstock . . . . . . . . . . . . . . . . . . . . . 22 

Pier/Wharf . . . . . . . . . . . . . . . . . . . . 23 
Page 

Pinnacle . . . . . . . . . . . . . . . . . . . . . . 49 

Pipeline . . . . . . . . . . . . . . . . . . . . . . 14 

Pipeline regulation station . . . . . . . . . . . 34 

Plain . . . . . . . . . . . . . . . . . . . . . . . . 49 

Point monument . . . . . . . . . . . . . . . . . 23 

Post . . . . . . . . . . . . . . . . . . . . . . . . 23 

Power site . . . . . . . . . . . . . . . . . . . . 34 

Principal meridian . . . . . . . . . . . . . . . 44 

Prospect . . . . . . . . . . . . . . . . . . . . . . 23 

Proving ground ................. 32 

Public survey area . . . . . . . . . . . . . . . 44 

Pump ....................... 23 

Racetrack . . . . . . . . . . . . . . . . . . . . . 23 

Railway . . . . . . . . . . . . . . . . . . . . . . 14 

Railway yard . . . . . . . . . . . . . . . . . . . 33 

Range ....................... 49 

Rapids ....................... 37 

Recreational slide . . . . . . . . . . . . . . . . 23 

Reef ........................ 50 

Reservation . . . . . . . . . . . . . . . . . . . . 39 

Reservoir . . . . . . . . . . . . . . . . . . . . . 24 

Rest site . . . . . . . . . . . . . . . . . . . . . 34 

Ridge ....................... 50 

Ridge line . . . . . . . . . . . . . . . . . . . . 50 

Road . . . . . . . . . . . . . . . . . . . . . . . . 15 

Rock ........................ 50 

Runway ...................... 24 

Sastrugi . . . . . . . . . . . . . . . . . . . . . . 50 

Sea/Ocean . . . . . . . . . . . . . . . . . . . . 37 

Shopping center . . . . . . . . . . . . . . . . . 28 

Shoreline . . . . . . . . . . . . . . . . . . . . . 38 

Shrubland . . . . . . . . . . . . . . . . . . . . . 35 

Sink ........................ 50 

Siphon ....................... 25 

Ski jump ..................... 25 

Snag/Stump . . . . . . . . . . . . . . . . . . . . 36 

Special use zone . . . . . . . . . . . . . . . . 42 

Spillway . . . . . . . . . . . . . . . . . . . . . . 25 

Sports site . . . . . . . . . . . . . . . . . . . . 29 

Page 

Spot elevation . . . . . . . . . . . . . . . . . . 47 

Spring ....................... 38 

S tate/f erritory . . . . . . . . . . . . . . . . . . 43 

Stream/River . . . . . . . . . . . . . . . . . . . 38 

Submerged stream . . . . . . . . . . . . . . . 38 

Substation . . . . . . . . . . . . . . . . . . . . . 35 

Summit ...................... 50 

Survey comer .................. 44 

Survey point . . . . . . . . . . . . . . . . . . . 44 

Tank ........................ 25 

Tank farm . . . . . . . . . . . . . . . . . . . . 32 

Taxiway ...................... 25 

Terrace ...................... 50 

Toll plaza . . . . . . . . . . . . . . . . . . . . . 34 

Tower ....................... 25 

Traffic inspection facility . . . . . . . . . . . 34 

Trail . . . . . . . . . . . . . . . . . . . . . . . . 16 

Trailer park . . . . . . . . . . . . . . . . . . . 32 

Transition area . . . . . . . . . . . . . . . . . . 33 

Transmission line . . . . . . . . . . . . . . . . 17 

Tree ........................ 36 

Trees ........................ 36 

Trench ....................... 50 

Tundra ....................... 45 

Tunnel ....................... 26 

Tunnel entrance . . . . . . . . . . . . . . . . . 26 

Turntable . . . . . . . . . . . . . . . . . . . . . 26 

Valley ....................... 50 

Wall ........................ 27 

Wash ....................... 50 

Water intake/outflow . . . . . . . . . . . . . . 27 

Waterfall . . . . . . . . . . . . . . . . . . . . . 39 

Well ........................ 27 

Well field . . . . . . . . . . . . . . . . . . . . . 31 

Wetland ...................... 45 

Winchnill . . . . . . . . . . . . . . . . . . . . . 27 

Wreck ....................... 27 

Wrecking yard . . . . . . . . . . . . . . . . . . 30 

Appendix A-11 
5. DLG-E FEATURE DOMAIN 

In this section, features are listed alphabetically under each view and subview 1, 2, and 3 headings. 

A definition is listed for each feature. Definitions for view and subview headings may be found on pages 10-13 of the 

main text of this circular. 

For each feature, all attributes with their associated attribute values are listed. For example: Barren land 

Attributes: Earth composition Values: Gravel 

Rock 

Salt 

Sand 

Shell 

Silt 

Unspecified 

Attributes of attribute values are also possible. Using "barren land" as an example, "rock type" is an attribute of the 

attribute value "rock" under the attribute "earth composition." This means that the attribute "rock type" applies only to 

the value "rock" under the attribute "earth composition." 

Attribute: Earth composition 

Value: Gravel 

Rock---------------->Attribute: Rock type 

Salt Values: Coral 

Sand Lava 

Shell Unspecified 

Silt Unknown 

Unspecified 

A-12 An Enhanced Digital Line Graph Design 
View: Cover Subview 1: Barren land 

Barren land 

Firebreak 

Ice mass 

Mud pot 

Earth composition 

Gravel 

Places composed of bare rock, sand, silt, gravel, or other earthen 

material with little or no vegetation and having limited ability to support 

life. 

Rock---------------> Rock type 

Salt Coral 

Sand Lava 

Shell Unspecified 

Silt Unknown 

Unspecified 

Ice mass type 

Alpine glacier 

Continental 

An area cleared of vegetation for the purpose of impeding the progress of a 

grass or forest fire. 

A field of ice, formed in regions of perennial frost. 

glacier-------->Continental glaciation type 

Pack ice 

Snowfield 

Inland ice sheet 

Ice shelf 

Name 

(Character identifier) 

Not applicable 

Unknown 

A pool of mud from which gas or vapors issue. 

View: Cover Subview 1: Built-up land Subview 2: Network 

Aqueduct 

Canal/Ditch 

Directional status 

One way 

Unknown 

Unspecified 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Canal/Ditch category 

Canal 

Ditch 

Unspecified 

A structure designed to transport water from a remote source, usually by 

gravity. 

An artificial waterway with no flow or a controlled flow used for navigation (canal), or for draining or irrigating land (ditch). 

Appendix A-13 
Canal/Ditch (continued) 

Cui de sac 

Pipeline 

Railway 

Directional status 

One way 

Unknown 

Unspecified 

Hydrographic category 

Intermittent 

Perennial 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Proposed 

Under construction 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Proposed 

Under construction 

Unknown 

Product 

Coal 

Sewage 

Water 

Unspecified 

Unknown 

Relationship to surface 

The round or circular section of the end of a dead-end stre~t. 

A tubular conduit of substantial length, with pumps, valves, and control 

devices, for conveying fluids, gases, or finely divided solids. 

Elevated above surface 

Submerged below water surface 

Under ground surface 

Number of lanes or tracks 

(Integer value) 

Unspecified 

Unknown 

A rail or set of parallel rails on which a train or trolley runs. 

A·14 An Enhanced Digital Line Graph Design 
Railway (continued) 

Road 

Operational status 

Abandoned 

Dismantled (Old railroad grade) 

Operational 

Under construction 

Unknown 

Railway category 

General case 

Inclined railway--->Inclined railway type 

Cable 

Logging 

Cog 

Unspecified 

Rapid transit (includes carline) 

Unknown 

Railway gauge 

Narrow 

Standard 

Monorail 

Unknown 

Railway type 

Mainline 

Siding 

Access restrictions 

None 

Private 

Restricted 

Toll 

Unknown 

Directional status 

Alternating 

Bidirectional 

One way 

Unspecified 

Unknown 

Median category 

With median 

Without median 

Name 

(Character identifier) 

Not applicable 

Unknown 

Number of lanes or tracks 

(Integer value) 

Unspecified 

Unknown 

Operational status 

Abandoned 

Operational 

Proposed 

Under construction 

Unknown 

An open way for passage of vehicles. 

Appendix A·1 5 
Road (continued) 

Trail 

Road class 

1st 

2nd 

3rd 

4th 

5th (4-wheel drive) 

Unknown 

Road type 

General case 

Overlook 

Ramp 

Rest area 

Runaway truck ramp 

Traffic circle 

Unknown 

Route designator 

(Alphanumeric identifier)------->Route type 

Unspecified 

Unknown Alternate 

Width (meters) 

(Integer value) 

Unspecified 

Access restrictions 

None 

Private 

Restricted 

Unknown 

Directional status 

Alternating 

Bidirectional 

One way 

Unspecified 

Unknown 

Historical significance 

Not significant 

Significant 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Business 

Bypass 

Connector 

Loop 

Spur 

Truck 

Unspecified 

A cleared path, beaten track, or improved surface, as throug'1- woods or 

wilderness, not usually trafficked by vehicles because of width, seasonal 

conditions, or access restrictions. 

A-16 An Enhanced Digital Line Graph Design 
Trail (continued) 

Trail type 

Bicycle 

Bridle 

Marked 

Pack 

Pedestrian 

Portage 

Ski 

Snowmobile 

Winter 

Unknown 

Not applicable 

Transmission line A system of wires that transmit electrical signals or electricity over distance. 

Operational status 

Operational 

Under construction 

Unknown 

Relationship to surface 

Elevated above surface 

Submerged below water surface 

Under ground surface 

Transmission Use 

Power 

Telegraph 

Telephone 

Unknown 

View: Cover Subview 1: Built-up land Subview 2: Structure 

Apron 

Athletic field 

Beacon 

Athletic field type 

Archery range 

Ball 

Equestrian 

Pistol range 

Polo 

Rifle range 

Unspecified 

Name 

(Character identifier) 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

A defmed paved area at an aircraft facility intended for aircraft parking. 

A defined but often unbounded open area constructed and maintained for 

the purpose of holding sporting events and activities. 

A visual, audible, or electronic signal for the guidance of marine or air 

navigation. 

Appen~lx A-17 
Beacon (continued) 

Boardwalk 

Breakwater/Jetty 

Bridge 

Navigation type 

Aeronautical-----------

Nautical 

Unknown 

Unspecified------------

Operational status 

Abandoned 

Operational 

Unknown 

Signaling method 

1--> Text 

I (Character identifier) 

I Not applicable 

Daybeacon 

Lighted----------->Lighthouse presence 

Radio 

Unspecified 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Operational 

Ruined 

Unknown 

Relationship to surface 

Exposed at surface 

With lighthouse 

Without lighthouse 

A promenade, especially of planks, along a beach or waterfront. 

Structure built to break the force of waves or to restrain or di--x;t current 

so as to protect a beach, harbor, or other waterfront facility. 

Submerged below water surface 

Covering 

Covered 

Not covered 

Name 

(Character identifier) 

Not applicable 

Unknown 

Number of decks 

(Integer value) 

Not applicable 

Unspecified 

Unknown 

A structure erected over a depression or obstacle to carry traffic. 

A-18 An Enhanced Digital Line Graph Design 
Bridge (continued) 

Building 

Cableway 

Chimney 

Cliff dwelling 

Operational status 

Abandoned 

Dismantled 

Operational 

Proposed 

Under construction 

Unknown 

Angle of orientation 

0 ... 89 degrees 

Not applicable 

Building class 

A permanent construction that is roofed and usually walled. 

Class 1---------------------1--> Text 

Class 2---------------------1 (Character identifier) 

Not applicable 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Ruined 

Unknown 

Cableway type 

Logging 

Ski lift 

Ski tow 

Tramway 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Dismantled 

Operational 

Unknown 

Chimney type 

Flare pipe 

Stack 

Unknown 

Angle of orientation 

0 ... 359 degrees 

A conveyor system in which carrier units run on wire cables strung between 

supports. 

A structure containing a passage or flue for discharging smoke or gases, or 

for burning waste gases. 

A habitat built in the recesses of high vertical or overhanging faces of r':lck. 

(Geological Survey shows only those sites protected by Federal or State 

authorizations.) 

Appen~~x- A·19 
Cliff Dwelling (continued) 

Conveyor 

Dam/Weir 

Name 

(Character identifier) 

Not applicable 

Unknown 

Material composition 

Earthen 

Masonry 

U~pecified 

Name 

(Character identifier) 

------Not applicable 

Unknown 

O~al status 

Operational 

Proposed 

Under construction 

U~wn 

Any permanent mechanism, such as a continuous moving belt, that 

transports bulk materials or packages from one place to anothe·. 

A barrier constructed to control the flow or raise the level of ~'·ater. 

Spillway elevation (Used when spillway not explicitly mapped) 

Dish 

Draw span 

Drilling platform 

(nearest 0.1 meter) 

(Numeric value) ------>Vertical datum category 

Product 

Gas 

Oil 

Unknown 

Relationship to surface 

Exposed at surface 

Guam Mean Sea Level Datum of 1963 

Mean sea level (local) 

National Geodetic Vertical Datum of 1929 

North American Vertical Datum of 1988 

Not applicable 

A concave object used for transmitting or receiving electronic signals. 

The movable portion of a bridge deck. 

A raised structure located in a sea equipped for the extraction o~ petroleum 

products. 

Submerged below water surface 

Drive-in theater screen The large, flat, white or silver surface (and supporting structure) upon 

which a picture is projected for viewing. 

Dry dock 

Flotation 

Floating 

Not floating 

An artificial basin fitted with a gate or caisson into which a ves:~~l may be 

floated and from which water may be pumped out to expose the bottom of 

the vessel. 

A·20 An Enhanced Digital Line Graph Design 
Fish ladder 

Flume 

Gaging station 

Gate 

Grave 

Helipad 

Directional status 

One way 

Unspecified 

Unknown 

Directional status 

One way 

Unspecified 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Product 

Coal 

Logs 

Oil 

Water 

Unspecified 

Unknown 

Gage type 

Tidal 

Unspecified 

Gate type 

Check-------- 1--->Text 

A facility consisting of a series of small pools, each one slightly higher 

than the preceding, built around a dam to enable fish to make their way 

upstream. 

An open, inclined, artificial channel constructed of wood, metal, or concrete 

generally elevated and V -shaped that carries liquid for a special purpose. 

A structure used to measure the condition of a hydrographic feature. 

A structure that may be swung, drawn, or lowered to block an entrance or 

passageway. 

Flood I (Character identifier) 

Head I Not applicable 

Road---------------->Access restrictions 

Sluice I Private 

Tidal I Toll 

Unspecified I Not applicable 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Surface condition 

Hard/Paved 

Not paved 

Unknown 

A place of burial for one person. 

A structure used for the landing and takeoff of helicopters. 

Appendix A·21 
Historical marker 

Kiln 

LaWtch pad 

LaWlching ramp 

Lock 

Masonry shore 

Mine entrance 

Penstock 

Name 

(Character identifier) 

Not applicable 

Unknown 

Product 

Brick 

Charcoal 

Coke 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Ramp type 

Boat 

Seaplane 

Name 

(Character identifier) 

Not applicable 

Unknown 

Angle of orientation 

0 .. .359 degrees 

Mine entrance type 

Adit 

Shaft 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Unknown 

A structure, not a building, that commemorates people or past events. 

Any of various ovens for hardening, burning, or drying substar~".es. 

A structure from which a rocket or missile is laWlched. 

A partially submerged hard surface on a shoreline for launchin~: or 

retrieving vessels or aircraft. 

An enclosure used to raise or lower vessels as they pass from c ne level to 

another. 

A structure built of stone, brick, or concrete that borders a body of water. 

Passage that affords entry to an WldergroWtd mine. 

A closed pipe or channel used to convey water into the turbine Clf a 

hydroelectric generating plant. 

A·22 An Enhanced Digital Line Graph Design 
Penstock (continued) 

Pier/Wharf 

Point monument 

Post 

Prospect 

Pump 

Racetrack 

Directional status 

One way 

Unspecified 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Operational 

Ruined 

Unknown 

Relationship to surface 

Exposed at surface 

Structures to which vessels may be berthed: 

Pier: long narrow structure extending into the water 

Wharf: parallel to the shoreline and accommodates ships O"' 

one side only 

Submerged below water surface 

Post type 

Dolphin 

Piling 

Name 

(Character identifier) 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Track condition/use 

A structure noting a spot on a boundary or survey line. 

An upright piece of timber or other material, in or adjacent to a body of 

water, used for mooring ships or supporting other structures. 

A marked location where mineral exploration has occurred but no mine has 

been developed. 

A device that raises, transfers, or compresses fluids or that attenuates ga~es 

especially by suction or pressure. 

A course laid out for racing. 

Hard/Paved-Vehicle 

Improved/Loose-Vehicle/Animal 

Improved-Pedestrian 

Improved/Rough-Vehicle 

Unknown 

Recreational slide An amusement structure consisting of a smooth, usually inclined surface. or 

track for sliding. 

Appendix A-23 
Reservoir 

Runway 

Covering 

Covered 

Not covered 

A constructed basin formed for recreation use, storage, treatme"'\t, collection, 

or processing of water or other liquids. 

Elevation (nearest 0.1 meter) 

(Numeric value)-->Vertical datum category 

Unspecified 

Unknown 

Hydrographic category 

Intermittent 

Perennial 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Reservoir use 

Clarification 

Cooling 

Guam Mean Sea Level Datum of 1963 

Mean sea level (local) 

National Geodetic Vertical Datum of 1929 

North American Vertical Datum of 1988 

Debris basin 

Evaporator--------------> Product 

Filtration bed Salt 

Fish hatchery Soda 

Fishpond Unknown 

Guzzler 

Industrial processing 

Industrial waste 

Percolation basin (spreading ground) 

Purification 

Retardation basin 

Settling basin 

Sewage disposal 

Storage----------------->Liquid contained 

Oil 

Water 

Sump-------------------->Liquid contained 

Oil 

Swimming 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Water 

A straight path used for landing and takeoff of aircraft. 

A·24 An Enhanced Digital Line Graph Design 
Runway (continued) 

Siphon 

Ski jump 

Spillway 

Tank 

Taxiway 

Tower 

Surface condition 

Hard/Paved 

Not paved 

Unknown 

A pipe conveying water by gravitational force to a lower level, over an 

obstruction higher than the intake. 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Directional status 

One way 

Unspecified 

Unknown 

An inclined structure consisting of a track from which skiers vault. 

A passage for surplus water to run over or around a dam. 

Elevation (nearest 0.1 meter) 

(Numeric value)-->Vertical datum category 

Name 

(Character identifier) 

Not applicable 

Unknown 

Tank type 

Cistern 

Guam Mean Sea Level Datum of 1963 

Mean sea level (local) 

National Geodetic Vertical Datum of 1929 

North American Vertical Datum of 1988 

Unspecified 

A large container used for storage. 

General case--------->Product 

Chemical 

Fuel 

Gas 

Gasoline 

Molasses 

Oil 

Oxygen 

Water 

Unspecified 

Silo--------------------> Product 

Grain 

Unknown 

Unspecified 

Storage bin----------->Product 

Surge 

Grain 

Unknown 

Unspecified 

An improved area providing access to/from runways and the apron. 

A structure designed primarily with a view to elevation, typically high~ 

than wide. 

Appendix A·25 
Tower (continued) 

Tunnel 

Tunnel entrance 

Turntable 

Height above surface level (meters) 

(Numeric value) 

Unspecified 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Unknown 

Tower function 

Control 

Cooling 

Electronic----->Electronic signal 

Microwave 

Radar 

Radio--------------- 1-->Call letters 

Television----------1 (Alpha identifier--3-4 characters) 

Unspecified--------1 Unspecified 

Unknown-----------1 

Observation---->Observ ation type 

Guard 

Lookout 

Mooring 

Pylon 

Support-------->Support type 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Operational 

Proposed 

Under construction 

Unknown 

Angle of orientation 

0 .. .359 degrees 

Operational status 

Abandoned 

Dismantled 

Operational 

Proposed 

Under construction 

Unknown 

Water intake tower 

Water 

Unknown 

Unspecified 

An underground or underwater passage. 

Opening that affords entry to an underground or underwal~ passage. 

A rotating platform with railroad tracks used for turning l'1comotives or 

cars. 

A·26 An Enhanced Digital Line Graph Design 
Wall 

Wall type 

General case 

Sea 

An upright structure of masonry, wood, plaster, or other building material 

serving to enclose, divide, or protect an area. 

Water intake/outflow A structure through which water enters or exits a conduit. 

Well 

Windmill 

Wreck 

Relationship to surface 

Exposed at surface 

Submerged below water surface 

Water intake/outflow type 

Riser-----------------> Text 

General case (Character identifier) 

Not applicable 

A pit or hole dug or bored into the Earth for the extraction of oil, water, 

other fluids or gases. 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Drill hole 

Operational 

Unknown 

Product 

Gas 

Heat 

Oil 

(Geothermal) 

Water--------------> Aow characteristics 

Unspecified Flowing 

Unknown Not flowing 

Hydrographic category 

Dry 

Not applicable 

Perennial 

Water characteristics 

Alkaline 

Hot 

Mineral 

Salt 

Unspecified 

A mill or other machine that runs on the energy generated by a wheel of 

adjustable blades or flats rotated by the wind. 

Name 

(Character identifier) 

Not applicable 

Unknown 

Windmill function 

Pump 

Generator 

The hulk or the ruins of a disabled vessel which is attached to or foul of 

the bottom or cast up on the shore. 

Appendix A·27 
Wreck (continued) 

Name 

(Character identifier) 

Not applicable 

Unknown 

Relationship to surface 

Exposed at surface-------------->Exposed portion 

Submerged below water surface 

Mast and(or) funnel 

Hull and(or) superstructure 

View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: Agriculture 

Fish hatchery 

Holding pen 

Name 

(Character identifier) 

Not applicable 

Unknown 

Holding pen type 

Corral 

Feedlot 

Stockyard 

Marine activity site 

A set of pools of water and related structures used for spawring and 

growing of fish that are subsequently used to stock lakes and streams. 

An enclosed area in which livestock are temporarily kept. 

A group of associated structures functioning as a unit used fC'"' fishing, 

aquaculture, or related activities. 

View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: Commercial 

Shopping center 

Name 

(Character identifier) 

Not applicable 

Unknown 

A group of structures used for the sa~e of products and services. 

View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: Entertainment/Recreational/Memorial 

Archeological site/Ruins An area of historical significance containing the deteriorated remains of a 

structure(s) or where past human life and activities are under study. 

Campground 

Archeological site/Ruins type 

Archeological site 

Pictograph 

Ruins 

Unspecified 

Name 

(Character identifier) 

Not applicable 

Unknown 

Campsite type 

A designated area on which primitive structure(s) are erected for 

temporary shelter or where recreational vehicles are temporarily parked. 

Campground (includes campsite) 

Recreational vehicle 

Unspecified 

A·28 An Enhanced Digital Line Graph Design 
Campground (continued) 

Cemetery 

Name 

(Character identifier) 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Exhibition ground 

Marina 

Outdoor theater 

Park 

Sports site 

Name 

(Character identifier) 

Nat applicable 

Unknown 

Name 

(Character identifier) 

Nat applicable 

Unknown 

Outdoor theater type 

Amphitheater 

Aqua 

Drive-in 

Name 

(Character identifier) 

Nat applicable 

Unknown 

Park type 

Amusement 

Botanical 

Parade ground 

Picnic area 

Playground 

Zoo 

Unspecified 

Name 

(Character identifier) 

Nat applicable 

Unknown 

An area of land for burying the dead with twa or mare graves. 

A public area where outdoor fairs, circuses, and ather events are held that 

also contains structures for the display of livestock, machinery, agricultural produce, etc. 

A harbor facility for recreational craft where supplies, repairs, and variorJS 

services are available. 

An outdoor area consisting of a stage or other focal point, and an area 

where the audience can be seated to view the performance or event 

A place or area developed for public use or recreation. 

A field, center, or open area maintained for the purpose of holding 

sporting events and activities. 

Appendix A ·29 
Sports site (continued) 

Sports site type 

Golf course----------

Gun club I 

Raceway I 

Rodeo grounds 1--> Text 

Ski area I (Character identifier) 

Stadium I Not applicable 

Tennis center--------

Name 

(Character identifier) 

Not applicable 

Unknown 

View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: Disposal 

Disposal site 

Wrecking yard 

Discarded substance 

Dredged material 

Garbage 

Slag pile 

Tailings 

Waste rock 

Unspecified 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

An area where refuse is dumped. 

(Spoil bank) 

(Dump, landfill) 

(Mine dump) 

An area or site engaged in the wrecking and reclamatio"' of discarded 

products. 

View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: Extraction 

Mine 

Mine type 

Auger borings 

Open pit 

Pit 

Placer 

Quarry 

Strip 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Reclaimed 

Unknown 

A·30 An Enhanced Digital Line Graph Design 

An excavation in the Earth for the purpose of extractinr Earth materials. 

Associated with linear strip mining, a method of extract~"'g minerals by 

boring horizontally into a seam. 

Removal of large deposits of mineral ores. 

Removal of unconsolidated materials. 

Surficial mining of alluvial or glacial deposits containin;-~ valuable 

minerals. 

Excavations in solid rock where building stone, limes tor~. etc., is 

removed. 

Excavations where overburden is removed to extract minerals (coal), 

leaving waste material piled at random. 
Mine (continued) 

Well field 

Product 

Bentonite 

Caliche 

Chert 

Cinders 

Clay 

Coal 

Copper 

Gold 

Gravel 

Pumice 

Salt 

Sand 

Scoria 

Shale 

Silver 

Soil 

Uranium 

Unspecified 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Unknown 

Product 

Gas 

Oil 

Unspecified 

Unknown 

An area where petroleum and(or) natural gas is or was removed 

from the Earth. 

View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: High Density Building Area 

High density building area A congested, built-up area. 

View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: Industrial 

Industrial site 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

A group of associated structures functioning as a unit used for refining a 

material or manufacturing a product. 

Appendix A ·31 
Industrial site (continued) 

Mineral pile 

Proving ground 

Tank farm 

Industrial plant type 

Ammunition 

Cannery 

Cement 

Filtration (includes waterworks) 

Refinery 

Sawmill 

Sewage disposal 

Unspecified 

Name 

(Character identifier) 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Product 

Gas 

Oil 

Unspecified 

A manmade heap of products resulting from mines. 

An area set aside for scientific testing. 

A set of tanks and related structures used for the storage of' liquids 

and(or) gases. 

View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: Institutional 

Institutional site 

Institutional function 

Civil government--- I 

Correctional I 

Education/Research I 

Historical I 

Medical I 

A group of buildings or associated structures functioning a.r a unit used 

predominantly for educational, correctional, governmental, nedical, or 

religious purposes. 

Military 1--> Text 

Orphanage I (Character identifier) 

Religious I Not applicable 

Unspecified I 

Unknown-------------1 

Name 

(Character identifier) 

Not applicable 

Unknown 

View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: Residential 

Trailer park 

Name 

(Character identifier) 

Not applicable 

Unknown 

An area maintained for the parking of inhabited mobile hores. 

A-32 An Enhanced Digital Line Graph Design 
View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: Transition 

Transition area Area in transition from one land use activity to another, and characterize1 

by a lack of information to predict future use or discern past use. 

View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: Transportation 

Aircraft facility 

Interchange 

Launch facility 

Parking site 

Railway yard 

Aircraft facility type 

Airport 

Heliport 

Seaplane base 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Interchange designator 

(Alphanumeric identifier) 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

An area where aircraft can take off and land, usually equipped with 

associated buildings and facilities. 

Facility used primarily by conventional, fixed-wing aircraft. 

Facility used primarily by rotary-wing aircraft. 

Facility used primarily where water is the landing surface. 

An area designated to provide traffic access from one road to another. 

An area from which rockets/missiles may be housed and projected, usua1ly 

equipped with associated buildings and facilities. 

A designated area where motor vehicles are set and left temporarily. 

An area provided with a system of tracks and associated 

structures where railway trains are assembled and railway 

cars are switched, stored, or serviced. 

Appendix A~3 
Railway yard (continued) 

Rest site 

Toll plaza 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Traffic inspection facility 

Traffic inspection facility type 

Agricultural 

Customs 

Weigh 

A roadside area usually having facilities for people and(or) vehicles. 

An open area having the facility to collect tolls. 

An open area having facilities to examine vehicles and(or) freir cargo. 

View: Cover Subview 1: Built-up land Subview 2: Complex Subview 3: Utility 

Cable/Pipeline site 

Dam site 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Pipeline regulation station 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Pipeline regulation station type 

Compressor 

Pumping 

Valve 

An area where cables or pipelines are located under water. 

An area including a dam and associated structures functionin.'! to control 

the flow or raise the level of water. 

An ancillary facility along a pipeline route in which the flow of fluids or 

gases is controlled. 

Power site A group of associated structures functioning as a unit q~t)d fpr geiU'~a~ electricity. 

A·34 An Enhanced Digital Line Graph Design 
Power site (continued) 

Substation 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

Power generation method 

Nuclear 

Solar 

Unknown 

Unspecified 

Name 

(Character identifier) 

Not applicable 

Unknown 

Operational status 

Abandoned 

Operational 

Under construction 

Unknown 

An ancillary facility along a powerline route in which electric current ir 

transformed. 

View: Cover Subview 1: Cultivated cropland 

Cultivated cropland 

Cultivated cropland type 

Nursery 

Orchard 

Vineyard 

Unspecified 

Unknown 

Vegetation type 

Cranberry 

Rice 

Unspecified 

Unknown 

Land that has been plowed or otherwise cultivated for crop production. 

View: Cover Subview 1: Vegetation Subview 2: Grassland 

Grassland An extensive noncultivated area where vegetation is dominated by gras~~s 

or grass-like plants. 

View: Cover Subview 1: Vegetation Subview 2: Shrubland 

Shrub land Areas covered with low-growing or stunted perennial vegetation and 

usually not mixed with trees. 

Appendix A-35 
View: Cover Subview 1: Vegetation Subview 2: Forestland 

Tree 

Trees 

Snag/Stump 

Name 

(Character identifier) 

Not applicable 

Unknown 

Tree category 

Deciduous 

Evergreen 

Vegetation characteristics 

Mangrove 

Unspecified 

Relationship to surface 

Exposed at surface 

Woody perennial plants having a self-supporting main stem C"t trunk and a 

definite crown. (Used for individual trees having historical or cultural 

significance.) 

An extensive area of land covered with woody perennial plat--t" having a 

self-supporting main stem or trunk and a definite crown. 

A firmly attached stem or trunk of a tree near the surface of water. 

Submerged below water surface 

View: Cover Subview 1: Water 

Area to be Submerged The known limits of the intended lake that will be created oobind a dam 

under construction. 

Elevation (nearest 0.1 meter) 

(Numeric value)--> Vertical datum category 

Unspecified 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Bay/Estuary/Inlet 

Ford 

Name 

(Character identifier) 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Guam Mean Sea Level Datum of 1963 

Mean sea level (local) 

National Geodetic Vertical Datum of 1929 

North American Vertical Datum of 1988 

A water area that is an inlet of the sea/ocean. 

Location in a body of water where the physical characteristiC"' of the 

bottom, water depth, and approaches permit the passage of vdlicles. 

Gut A narrow natural passage or contracted strait connecting two bodies of 

water where no flow can be determined. 

A·36 An Enhanced Digital Line Graph Design 
Gut (continued) 

Inundation area 

Lake/Pond 

Rapids 

Sea/Ocean 

Name 

(Character identifier) 

Not applicable 

Unknown 

An area of land subject to flooding. 

Inundation control 

Controlled-------->lnundation area use 

Dewatering area 

Duck pond 

Not controlled 

A standing body of water surrounded by land. 

Elevation (nearest 0.1 meter) 

(Numeric value)-->Vertical datum category 

Guam Mean Sea Level Datum of 1963 

Mean sea level (local) 

National Geodetic Vertical Datum of 1929 

North American Vertical Datum of 1988 

-->Stage 

Unspecified 

Unknown 

Hydrographic category 

Intermittent 

Perennial 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Water characteristic 

Fresh 

Salt 

Average water elevation 

High water elevation 

Normal pool elevation 

An area of swift current in a stream or river, characterized by standing 

waves or by boulders and rocks. 

Directional status 

One way 

Unknown 

Unspecified 

Name 

(Character identifier) 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

Sea/Ocean type 

Reef pool 

Unspecified 

The great body of salt water of the oceans. 

Appendix /t.-37 
Shoreline 

Spring 

Stream/River 

Delineation status 

Apparent 

Definite 

Indefmite/ 

Approximate 

Unsurveyed 

Angle of orientation 

0 ... 359 degrees 

Name 

(Character identifier) 

Not applicable 

Unknown 

Water characteristics 

Alkaline 

Hot 

Mineral 

Sulfur 

Unspecified 

Delineation status 

Definite 

Unsurveyed 

A naturally occurring line of contact between a body of water and the 

land. 

A place where water issues from the ground naturally. 

A body of flowing water. 

Elevation (nearest 0.1 meter) 

(Numeric value)-->Vertical datum category 

Guam Mean Sea Level Datum of 1963 

Mean sea level (local) 

National Geodetic Vertical Datum of 1929 

North American Vertical Datum of 1988 

-->Stage 

Unspecified 

Unknown 

Directional status 

One way 

Unknown 

Unspecified 

Hydrographic category 

Intermittent 

Perennial 

Unknown 

Hydrographic form 

Braided 

Not braided 

Name 

(Character identifier) 

Not applicable 

Unknown 

Normal pool elevation 

Submerged stream An old river course inundated by an impounded water ana. 

A-38 An Enhanced Digital Line Graph Design 
Submerged stream (continued) 

Name 

(Character identifier) 

Not applicable 

Unknown 

Waterfall A vertical or nearly vertical descent of water over a step or ledge in the 

bed of a river. 

Name 

(Character identifier) 

Not applicable 

Unknown 

View: Division Subview 1: Administrative 

Reservation Bounded land set aside for a particular purpose generally having certain 

use restrictions. 

Name 

(Character identifier) 

Not applicable 

Unknown 

Reservation class 

Forest----------------- I 

General case I 

Grassland I 

Indian land I 

Military 1--> Text 

Park I (Character identifier) 

Prison I Not applicable 

Wilderness I 

Wildlife I 

Unknown-------------1 

Reservation use status 

National 

State 

Regional 

County 

Minor civil unit 

City 

Private 

Unknown 

View: Division Subview 1: Boundary 

Boundary Line A separation between divisions of current or past significance. 

Delineation status 

Definite 

Disputed 

Historical 

Indefinite/Approximate 

Proposed-------------1---> Text 

Protracted-·----------1 (Character identifier) 

Unknown Not applicable 

Name 

(Character identifier) 

Not applicable 

Unknown 

Appendix A-39 
Boundary point 

Fence line 

Boundary point identifier 

(Alphanumeric identifier) 

Not applicable 

Unknown 

International Date Line 

View: Division Subview 1: Census 

An identified location on a boundary. 

An identifiable fence or field line visible on an aerial photorraph. 

A line generally coinciding with the 180th meridian, modifie~ to avoid 

land, and designated as the place where each calendar day b~gins. 

Census block The primary statistical unit for which census information is ~ollected and 

published. 

Census block number 

(Alphanumeric value) 

Census block group 

Census block group number 

(Integer value - 1-9) 

Census County Division (CCD)/ 

Minor Civil Division (MCD) 

CCDJMCD number 

(Integer value - 001-999) 

Census tract/Block Numbering Area (BNA) 

Census tract/BNA Number 

An aggregate of census blocks for which statistical information is 

published. 

Subcounty aggregates of census tracts and Block Numbering Areas 

(BNA's) for which statistical information is published. CCD's 

are established in areas where MCD's do not exist. 

Aggregates of census block groups for which statistical infon"'~ation is 

published. Tracts occur in MSA's and potential MSA's, and BNA's 

occur outside MSA's. 

(Numeric value - 0001.01-9989.99) 

Metropolitan Statistical Area (MSA) An area with a population greater than 50,000. 

MSA type 

Part MSA (PMSA) 

Consolidated MSA (CMSA) 

General case 

MSA PIPS code 

(Integer value - 0001-9999) 

View: Division Subview 1: Hydrologic unit 

Hydrologic Unit Subdivisions used for the collection and organization of data dealing with 

the properties, distribution, and circulation of water. These codes provide 

a standardized base for use by water resources organizations in the 

storage. retrieval, and exchange of hydrologic data; the indexi""~ and 

inventorying of hydrologic data and information; the catalogin~ of water 

data acquisition activities; and a variety of other applications. 

Region unit code 

(Integer value - 01...21) 

Subregion unit code 

(Integer value - 01...99) 

Not applicable 

A-40 An Enhanced Digital Line Graph Design 
Hydrologic unit (continued) 

Acc01mting unit code 

(Integer value - 00 ... 99) 

Not applicable 

Cataloging unit code 

(Integer value - 00 ... 99) 

Not applicable 

Name 

(Character identifier) 

Unknown 

View: Division Subview 1: Land parcel 

Land parcel A tract or plot of the Earth's surface distinguishable by ownership. 

Ownership 

National---------->Owning agency 

State Agricultural Research Service 

Air Force 

View: Division Subview 1: Locale 

Anny 

Anny (Corps of Engineers -

Civil Works) 

Bonneville Power Administration 

Bureau of Indian Affairs 

Bureau of Land Management 

Bureau of Mines 

Bureau of Prisons 

Bureau of Reclamation 

Energy Research and Development 

Administration 

Federal Aviation Administration 

Federal Railroad Administration 

Fish and Wildlife Service 

Forest Service 

General Services Administration 

International Boundary and Water 

Commission, United States 

and Mexico 

National Aeronautics and Space 

Administration 

National Oceanic and Atmospheric 

Administration 

National Park Service 

Navy 

Tennessee Valley Authority 

U.S. Coast Guard 

Veterans' Administration 

Locale A named place not otherwise categorized. 

Name 

(Character identifier) 

Unknown 

View: Division Subview 1: Maritime 

Anchorage An area where a vessel anchors or may anchor, either because of suit"'~ 

bility or designation. 

Appendix A-41 
Anchorage (continued) 

Hazard zone 

Lane 

Anchorage type 

Explosives isolation 

General case 

Seaplane 

Name 

(Character identifier) 

Not applicable 

Unknown 

Hazard zone type 

Crib 

Foul ground 

Mine danger area 

Piling 

Platform 

Reef 

Rock 

Snag/Stump 

Unknown 

Unspecified 

Well 

Wreckage 

Lane type 

Airboat trail 

Dredged channel 

Ferry crossing 

Seaplane landing/takeoff 

Shipping 

Name 

(Character identifier) 

Not applicable 

Unknown 

Special use zone 

Special use activity 

An area identified as a danger to maritime navigation. 

A prescribed course for ships, boats, or seaplanes. 

An area where distinctive types of shipping activities occur. 

Dumping ground for hazardous material 

Spoil area 

View: Division Subview 1: Political 

City An incorporated populated place such as a village, city, town, borough, or 

hamlet, and includes an independent city. 

County 

Name 

(Character identifier) 

PIPS code identifier-2nd 

(Integer value - 001...999) 

Name 

(Character identifier) 

Second-order division of a nation such as parish, borough, county, 

municipio, or judicial division, and independent cities in Mary1 "'nd, 

Missouri, Nevada, and Virginia. 

A-42 An Enhanced Digital Line Graph Design 
Exclusive Economic Zone (EEZ) 

Minor civil unit 

FIPS code identifier-3rd 

A zone contiguous to the territorial sea, including zones contiguous to the 

territorial sea of the United States, Puerto Rico, the Northern Mariana 

Islands, and U.S. overseas territories and possessions. The EEZ extends 

to a distance 200 nautical miles from the baseline from which the breadth 

of the territorial sea is measured. In cases where the maritime boundary 

with a neighboring state remains to be determined, the boundary of the 

EEZ shall be determined by the U.S. and other states concerned in accordance with equitable principles. 

Third-order division of a nation such as township, town, district, precinct, 

and barrio. 

(Integer value - 0001...9999) 

Not applicable 

Name 

(Character identifier) 

Minor civil subunit 

Nation 

State/Territory 

Name 

(Character identifier) 

Name 

(Character identifier) 

FIPS code identifier-1st 

(Integer value - 01...99) 

Name 

(Character identifier) 

View: Division Subview 1: Survey system 

Fourth-order division of a nation such as Hawaiian ahupuaas. 

An area under the jurisdiction of a sovereign government. 

First-order division of a nation. 

Baseline The line extending east and west from the initial point of a Public Lan~ 

Survey System (PLSS) survey. Townships will be north or south of th~ 

baseline. 

Name 

(Character identifier) 

Georgia Survey District 

District number 

(Integer value - 001...999) 

Lot number 

Public lands surveyed by the State of Georgia from 1805-1832. The land 

was divided by county into districts and lots. The State contains 389 

districts, and each district can have over 1,000 lots. The lots were siz,~d 

according to their perceived value and range from 40 to 490 acres. 

Generally these land lines have NOT been shown on 7 .5-minute quadrangles except in the Atlanta area. 

(Integer value - 0001...9999) 

Homestead entry Title to portions of the public domain was granted to individuals unda 

various homestead acts, based on residence, cultivation, and some improvement to the land over several years. Homestead entries are not 

normally identified on published maps. 

Appen..tlx A-43 
Land grant Grants established prior to the original subdivisional public swveys. 

Land grant code 

(Integer value - 0001 ... 7302) 

Unknown 

Name 

(Character identifier) 

Unknown 

Principal meridian The line extending north and south from the initial point of a Public Land 

Survey System (PLSS) survey. Townships will be east or west of the 

principal meridian. 

Public survey area An area of the public land survey systems established by pubPr-.. private, 

or combined surveys. 

Survey comer 

Survey point 

Origin of survey name 

(Character identifier) 

Origin of survey number 

(Integer value - 01...48) 

Public survey area type 

General case 

Donation land claim 

Range number 

(Numeric value with 1 alpha character (E/W}} 

Section number 

(Alphanumeric value) 

Township number 

(Numeric value with 1 alpha character (N/S}} 

BLM comer identifier 

(Alphanumeric value) 

Field identification 

Identified 

Not identified 

Unknown 

Name 

(Character identifier) 

Survey comer type 

Arbitrary 

Auxiliary meander 

Closing 

Isolated 

Land grant 

Meander 

Quarter section 

Section 

Tract 

Witness off line 

Witness on line 

Survey point type 

Angle point 

Land grant monument 

A public land survey or other land survey comer. 

A survey location other than a survey comer. 

Location monument (includes mineral monument) 

A-44 An Enhanced Digital Une Graph Design 
Survey point (continued) 

Survey point type (continued) 

Reference monument 

Witness point 

Monument number 

(Integer value) 

Not applicable 

View: Ecosystem 

Desert 

Tundra 

Wetland 

Name 

(Character identifier) 

Not applicable 

Unknown 

Name 

(Character identifier) 

Not applicable 

Unknown 

A region rendered barren or partially barren by environmental extremes, 

especially by low rainfall. 

A treeless, level, or gently rolling plain characteristic of arctic or subarctic 

regions, having a permanently frozen subsoil, and usually supporting lmv 

growing vegetation such as lichens, mosses, and stunted shrubs. 

A vegetated area that is inundated or saturated by surface or ground W2'ter 

for a significant part of the year. The vegetation is adapted for life in 

saturated soil conditions. 

View: Geoposition 

Contour (bathymetric) A line cormecting points of equal depth with reference to the sounding 

datum. 

Contour symbolization category 

Mound 

Not applicable 

Delineation status 

Amended 

Definite 

Indefinite/ 

Approximate 

Depth (nearest 0.1 meter) 

(Positive Numeric Value)----->Bathymetric datum 

Gulf Coast low water 

Lowest low water 

Mean low lake level 

Mean low water 

Mean lower low water 

Mean sea level 

Tropic lower low water 

Water surface as indicated--->Text 

(Character identifier) 

Unknown 

Appen ~~X A-45 
Contour (land) 

Control station 

Mile marker 

Contour symbolization category 

Depression 

Not applicable 

Delineation status 

Amended 

Definite 

Indefinite/ 

Approximate 

Elevation (nearest 0.1 meter) 

A line connecting points of equal elevation with reference to a vertical 

datum. 

(Numeric value)-->Vertical datum category 

Guam Mean Sea Level Datum of 1963 

Mean sea level (local) 

National Geodetic Vertical Datum of 1929 

North American Vertical Datum of 1988 

A point with an accurate position and(or) elevation used as a base for a 

dependent survey. 

Elevation (nearest 0.001 meter) 

(Numeric value)-->Vertical datum category 

Unspecified 

Horizontal control accuracy 

First order 

Not applicable 

Guam Mean Sea Level Datum of 1963 

Mean sea level (local) 

National Geodetic Vertical Datum of 1929 

North American Vertical Datum of 1988 

Second order-------- 1-->Control class 

Third order---------· I Class I 

Third order or better Class ll 

Monument type 

No tablet 

Tablet 

Name 

(Character value) 

Not applicable 

Unknown 

Relationship to surface 

Elevated above surface 

Exposed at surface 

Vertical control accuracy 

First order----------- I 

Not applicable 1-->Control class 

Second order-------- I Class I 

Third order Class ll 

Third order or better 

Mile marker type 

Railroad 

Watercourse 

A point on a feature indicating the distance, in miles, measured along the 

course or path of the feature, from an established origin point C'n the 

feature. 

Mileage number (nearest 0.1 mile) 

(Numeric value) 

A-48 An Enhanced Digital Une Graph Design 
Spot elevation 

Elevation (nearest 0.1 meter) 

A point with a measured vertical position, measured relative to a reference datum, of less than third-order accuracy. 

(NliJlleric value)-->Vertical datum category 

Guam Mean Sea Level Datum of 1963 

Mean sea level (local) 

National Geodetic Vertical Datum of 1929 

North American Vertical Datum of 1988 

Relationship to surface 

Elevated above surface 

Exposed at surface 

View: Morphology 

Arch 

Bar 

Basin 

Beach 

Bend 

Cape 

Cave 

Name 

(Character identifier) 

Bar type 

Offshore 

Point 

Name 

(Character identifier) 

Not applicable 

Basin type 

Carolina Bay 

A naturally occurring curved structure that supports the weight of material 

over space. 

A natural accumulation of sand, gravel, or other material forming an 

underwater or exposed embankment 

A bowl-shaped depression in the surface of the land or ocean floor. 

Crater --------------->Crater type 

Unspecified 

Name 

(Character identifier) 

Name 

(Character identifier) 

Name 

(Character identifier) 

Name 

(Character identifier) 

Name 

(Character identifier) 

Bomb 

Meteoric 

Volcanic 

The gently sloping shore that is washed by waves, usually composed of 

sand and pebbles. 

The land within the curve of a stream sometimes including the course of 

the stream. 

A projection of land extending into a body of water that prominently 

marks a change in or interrupts the coastal trend of that water body. 

A naturally formed, subterranean open area or chamber. 

Appenrtlx A-47 
Cave entrance 

Cliff 

Crevasse 

Angle of orientation 

0 ... 359 degrees 

Name 

(Character identifier) 

Name 

(Character identifier) 

Disturbed surface 

Dunes 

Embankment 

Fault 

Flat 

Foreshore 

Fumarole 

Gap 

Name 

(Character identifier) 

Not applicable 

Stability 

Stable 

Shifting 

Embankment type 

Levee 

Redoubt 

Name 

(Character identifier) 

Not applicable 

Flat type 

Playa 

Tidal 

Name 

(Character identifier) 

Not applicable 

Name 

(Character identifier) 

Not applicable 

Name 

(Character identifier) 

Not applicable 

A·48 An Enhanced Digital Une Graph Design 

Passage that affords entry to a naturally formed, subterranean open area or 

chamber. 

A high vertical, near-vertical, or overhanging face of rock, earth. or ice. 

A deep fissure in the surface of the Earth caused by breaking or parting. 

An area that is broken into a chaotic pattern of elevations and depressions. 

Hills of sand piled up by the wind. 

A raised, solid-fill linear mound. 

A fracture in the Earth's crust accompanied by a displacement of one side 

of the fracture with respect to the other. 

A level tract of land. 

The part of a seashore between high-water and low-water mark~ 

A hole in the Earth's crust from which steam and gases are 

emitted. 

A low point or opening between mounts or in a ridge. ' ' ~~ 
Geyser 

Name 

(Character identifier) 

Not applicable 

Unknown 

Iceberg 

Iceberg tongue 

Incline/Flow 

Name 

(Character identifier) 

Island 

Name 

(Character identifier) 

Not applicable 

Isthmus 

Name 

(Character identifier) 

Moraine 

Name 

(Character identifier) 

Not applicable 

Mount 

MoWlt type 

General case 

Hummocked ice 

Ice dome 

Indian mound 

Pin go 

Name 

(Character identifier) 

Pinnacle 

Name 

(Character identifier) 

Plain 

Name 

(Character identifier) 

Range 

Name 

(Character identifier) 

A natural intermittent fountain of hot water ejected with force into the ai":' 

from a hole in the Earth's crust. 

Large mass of floating or stranded ice of greatly varying shape, more than 

5 meters above sea level, which has broken away from a glacier. 

A major accumulation of icebergs projecting from the coast, held in place 

by grounding and joined together by fast ice. 

A feature characterized by a sloping surface or a formation resulting from 

movement down a sloping surface. 

An area of dry or relatively dry land surrounded by water or low wetlarri. 

A narrow strip of land, bordered on both sides by water that comects t"wo 

larger land areas. 

An accumulation of earth and stones carried and deposited by a glacier. 

A landmass that projects conspicuously above its surroundings. 

A vertical, standing, often spire-shaped natural rock formation. 

A region of general uniform slope, comparatively level and of considerable extent. 

A chain of mounts. 

Appenrllx A-49 
Reef 

Ridge 

Ridge line 

Rock 

Sastrugi 

Sink 

Sununit 

Terrace 

Trench 

Valley 

Wash 

Name 

(Character identifier) 

Not applicable 

Name 

(Character identifier) 

Name 

(Character identifier) 

Relationship to surface 

Awash 

Exposed at surface 

A chain of rocks or coral at or near the surface of water. 

A long and narrow upland with steep sides. 

The line separating drainage basins. 

A concreted mass of stony material. 

Submerged below water surface 

Name 

(Character identifier) 

Not applicable 

Name 

(Character identifier) 

Name 

(Character identifier) 

Name 

(Character identifier) 

Name 

(Character identifier) 

Not applicable 

Sharp, irregular ridges formed on a snow surface by wind erosion and 

deposition. The ridges are parallel to the direction of the preYailing wind. 

The place at which a stream disappears underground in a karst area. 

The peak of a mount or ridge. 

A step-like land surface between higher and lower ground. 

A long cut in the surface created through excavation. 

An elongated depression in the Earth's surface that generally shpes from 

one end to the other. 

The dry portion of a bed of a stream that contains water only during or 

after a local rainstorm or heavy snowmelt. 

A·SO An Enhanced Digital Line Graph Design 
6. ALPHABETIC LIST OF DLG-E ATTRIBUTES AND ASSOCIATED ATTRIBUTE VALUES 

This section lists alphabetically all DLG-E attributes and all possible attribute values and identifies the features to whicll 

a value is associated. For example, the entry for the attribute "water characteristics" appears as follows: 

Water characteristics 

Alkaline -Spring, (Well) 

Fresh -Lake/Pond 

Hot -Spring, (Well) 

Mineral -Spring, (Well) 

Salt -Lake/Pond, (Well) 

Sulfur -Spring 

Unspecified -Spring, (Well) 

The attribute "water characteristics" will be found for the features Lake/Pond, Spring, and (Well). The feature "well" is 

in parentheses to indicate that the attribute "water characteristics" is an attribute of an attribute value included under the 

feature "well" (it is not directly an attribute of the feature itself). 

The attribute values of "water characteristics" are different for each of the features listed above. 

Feature: 

Attribute: 

Values: 

Feature: 

Attribute: 

Lake/Pond 

Water characteristics 

Fresh and Salt 

Spring 

Water characteristics 

Values: Alkaline, Hot, Mineral, Sulfur, Unspecified 

Feature: 

Attribute: 

(Well) 

Product 

Value: Water------->Attribute: Water characteristics 

Value: Alkaline 

Access restrictions 

None -Road, Trail 

Hot 

Mineral 

Salt 

Unspecified 

Private 

Restricted 

Toll 

-(Gate), Road, Trail 

-Road, Trail 

-(Gate), Road, 

Not applicable 

Unknown 

-(Gate) 

-Road, Trail 

Accounting unit code 

(Integer value (00 ... 99)) 

Not applicable 

Aircraft facility type 

-Hydrologic Unit 

Airport -Aircraft facility 

Heliport 

Seaplane base 

Anchorage type 

Explosives isolation 

General case 

Seaplane 

Angle of orientation 

-Anchorage 

0 ... 89 -Building 

0 ... 359 -Cave entrance, Cliff dwelling, Mine entrance, Spring, Tunnel entrance 

Not applicable -Building 

Appen dlx A·51 
Archeological site/Ruins type 

Archeological site -Archeological site/Ruins 

Pictograph 

Ruins 

Unspecified 

Athletic field type 

Archery range -Athletic field 

Ball 

Equestrian 

Pistol range 

Polo 

Rifle range 

Unspecified 

Bar type 

Offshore -Bar 

Point 

Basin type 

Carolina bay -Basin 

Crater 

Unspecified 

Boundary point identifier 

(Alphanumeric identifier) 

Not applicable 

Unknown 

Building class 

Class 1 

Class 2 

-Building 

-Boundary point 

Bureau of Land Management (BLM) identification number 

(Alphanumeric value) -Survey comer 

Building class 

Class 1 -Building 

Class 2 

Cableway type 

Logging -Cableway 

Ski lift 

Ski tow 

Tramway 

Unknown 

Campsite type 

Campground 

Recreational vehicle 

Unspecified 

Canal/Ditch category 

-Campground 

Canal -Canal/Ditch 

Ditch 

Unspecified 

Cataloging unit code 

(Integer value (00 ... 99)) -Hydrologic unit 

Not applicable 

Census block group number 

(futeger value - 1-9) -Census block group 

Census block number 

(Alphanumeric value) -Census block 

A-52 An Enhanced Digital Line Graph Design 
Census County Division (CCD)/ 

Minor Civil Division (MCD) number 

(Integer value - 001-999) -CCD/MCD 

Census tract/Block Numbering Area (BNA) number 

(Numeric value - 0001.01-9989.99) -Census tract/BNA 

Chimney type 

Flare pipe 

Stack 

Unknown 

-Chimney 

Contour symbolization category 

Depression -Contour (land) 

Mound -Contour (bathymetric) 

Not applicable -Contour (bathymetric), Contour (land) 

Covering 

Covered -Bridge, Reservoir 

Not covered 

Cultivated cropland type 

Nursery -Cultivated cropland 

Orchard 

Vineyard 

Unspecified 

Unknown 

Delineation status 

Amended 

Apparent 

Definite 

Disputed 

Historical 

Indefinite/ 

Approximate 

Proposed 

Protracted 

Unsurveyed 

Unknown 

Depth 

-Contour (bathymetric), Contour (land) 

-Shoreline 

-Boundary line, Contour (bathymetric), Contour (land), Shoreline, Stream/River 

-Boundary line 

-Boundary line 

-Boundary line, Contour (bathymetric), Contour (land), Shoreline 

-Boundary line 

-Boundary line 

-Shoreline, Stream/River 

-Boundary line 

(Positive numeric value) -Contour (bathymetric) 

Discarded substance 

Dredged material 

Garbage 

-Disposal site 

Slag pile 

Tailings 

Waste rock 

Unspecified 

Unknown 

District number 

(Integer value - 001. .. 999) 

Earth composition 

Gravel -Barren land 

Rock 

Salt 

Sand 

Shell 

Silt 

Unspecified 

-Georgia Survey District 

Appen ~lx A-53 
Elevation 

(Numeric value -nearest 0.001 meter) 

(Numeric value -nearest 0.1 meter) 

Unspecified 

Unknown 

Embankment type 

Levee -Embankment 

Redoubt 

FIPS code identifier-1st 

-Control station 

-Area to be submerged, Contour (land), Lake/Pond, Reservdr, Spillway, 

Spot elevation, Stream/River 

-Area to be submerged, Control station, Lake/Pond, Reservdr, Spillway, 

Stream/River 

-Area to be submerged, Lake/Pond, Reservoir, Stream/River 

(Integer value - 01. .. 99) -State/Territory 

FIPS code identifier-2nd 

(Integer value - 001...999) -County 

FIPS code identifier-3rd 

(Integer value - 0001...9999) -Minor Civil Unit 

Not applicable 

Field identification 

Identified -Survey comer 

Not identified 

Unknown 

Flat type 

Playa -Flat 

Tidal 

Flotation 

Floating -Drydock 

Not floating 

Directional status 

Alternating 

Bidirectional 

One way 

Unspecified 

Unknown 

Gage type 

-Road, Trail 

-Road, Trail 

-Aqueduct, Canal/Ditch, Fish ladder, Flume, Penstock, Rapids, Road, Siphon, St··~am/River, 

Trail 

-Aqueduct, Canal/Ditch, Fish ladder, Flume, Penstock, Rapids, Road, Siphon, Str~am/River 

Trail 

-Aqueduct, Canal/Ditch, Fish ladder, Flume, Penstock, Rapids, Road, Siphon, Stream/River, 

Trail 

Tidal -Gaging station 

Unspecified 

Gate type 

Check -Gate 

Flood 

Head 

Road 

Sluice 

Tidal 

Unspecified 

Hazard zone type 

Crib -Hazard zone 

Foul ground 

Mine danger area 

Piling 

Platform 

Reef 

Rock 

Snag/Stump 

Unknown 

A-54 An Enhanced Digital Line Graph Design 
Hazard zone type (continued) 

Unspecified 

Well 

Wreckage 

Height above surface level (meters) 

(Numeric value) -Tower 

Unspecified 

Unknown 

Historical significance 

Not significant -Trail 

Significant 

Unknown 

Holding pen type 

Corral -Holding pen 

Feedlot 

Stockyard 

Horizontal control accuracy 

1st order -Control station 

2nd order 

3rd order 

3rd order or better 

Not applicable 

Hydrographic category 

Dry -(Well) 

Intermittent -Canal/Ditch, Lake/Pond. Reservoir. Stream/River 

Perennial -Canal/Ditch, Lake/Pond. Slr~iver, (Well) 

Not applicable -Reservoir, (Well) 

Unknown -Canal/Ditch, Lake/Pond, Reservoir, Stream/River 

Hydrographic form 

Braided -Stream/River 

Not braided 

Ice mass type 

Alpine glacier -lee mass 

Continental glacier 

Pack ice 

Snowfield 

Industrial plant type 

Ammunition -Industrial site 

Cannery 

Cement 

Filtration 

Refinery 

Sawmill 

Sewage disposal 

Unspecified 

Institutional function 

Civil government -Institutional site 

Correctional 

Education/Research 

Historical 

Medical 

Military 

Orphanage 

Religious 

Unspecified 

Unknown 

Append~-« A-55 
Interchange designator 

(Alphanumeric identifier) 

Not applicable 

Unknown 

Inundation control 

-Interchange 

Controlled -Inundation area 

Not controlled 

Land grant code 

(Integer value - 0001...7302) -Land grant 

Unknown 

Lane type 

Airboat trail -Lane 

Dredged channel 

Ferry crossing 

Seaplane landing/takeoff 

Shipping 

Lot number 

(Integer value - 0001-9999) -Georgia Survey District 

Material composition 

Earthen -Dam/Weir 

Masonry 

Unspecified 

Median category 

With median -Road 

Without median 

Metropolitan Statistical Area PIPS code 

(Integer value - 01-9999) -Metropolitan Statistical Area (MSA) 

Metropolitan Statistical Area (MSA) type 

Part MSA (PMSA) -Metropolitan Statistical Area (MSA) 

Consolidated MSA (CMSA) 

General case 

Mile marker type 

Railway -Mile marker 

Watercourse 

Mileage number 

(Numeric value) 

Mine entrance type 

-Mile marker 

Adit -Mine entrance 

Shaft 

Mine type 

Auger borings -Mine 

Open pit 

Pit 

Placer 

Quarry 

Strip 

Monument number 

(Integer value) -Survey point 

Not applicable 

Monument type 

No tablet -Control station 

Tablet 

A-56 An Enhanced Digital Line Graph Design 
Mount Type 

General case 

Hummocked ice 

Ice dome 

Indian mound 

Pin go 

Name 

(Character 

identifier) 

Not applicable 

Unknown 

Navigation type 

Aeronautical 

Nautical 

Unspecified 

Unknown 

Number of decks 

(Integer value) 

Not applicable 

Unspecified 

Unknown 

-Mount 

-Aircraft facility, Anchorage, Aqueduct, Arch, Archeological site/Ruins, Area to be submerged, 

Athletic field, Bar, Baseline, Basin, Bay/Estuary/Inlet, Beach, Beacon, Bend, Boardwalk, Boundary 

line, Breakwater/Jetty, Bridge, Building, Cableway, Campground, Canal/Ditch, Cape, Cave, Cave 

entrance, Cemetery, City, Cliff, Cliff dwelling, Control station, County, Cul de sac, Dam site, 

Dam/Weir, Desert, Dunes, Exhibition ground, Fault, Fish hatchery, Flat, Ford, Fumarole, Gap, 

Geyser, Gut, Helipad, Historical marker, Hydrologic unit, Ice mass, Incline/Flow, Industrial site, 

Institutional site, Interchange, Island, Isthmus, Lake/Pond, Land grant, Lane, Launch facility, LalUl~h 

pad, Locale, Lock, Marina, Mine, Mine entrance, Minor Civil Unit, Minor Civil Subunit, Moraine. 

Mount, Nation, Outdoor theater, Park, Pier/Wharf, Pinnacle, Pipeline, Pipeline regulation station, 

Plain, Power site, Prospect, Proving ground, Racetrack, Railway yard, Range, Rapids, Reef, 

Reservation, Reservoir, Rest site, Ridge, Ridge line, Road, Sea/Ocean, Shopping center, Sink, Spo·ts 

site, Spring, State/Territory, Storage site, Stream/River, Submerged stream, Substation, Summit, 

Survey comer, Tank, Tank farm, Terrace, Tower, Trail, Trailer park, Tree, Tunnel, Valley, Wash, 

Waterfall, Well, Well field, Wetland, Windmill, Wreck 

-Beacon 

-Bridge 

Number of lanes or tracks 

(Integer value) -Railway, Road 

Unspecified 

Unknown 

Operational status 

Abandoned 

Dismantled 

Drill hole 

Operational 

Proposed 

Reclaimed 

Ruined 

Under construction 

Unknown 

Origin of survey name 

(Character identifier) 

-Aircraft facility, Aqueduct, Beacon, Bridge, Building, Cableway, Canal/Ditch, Dam site, 

Disposal site, Flume, Helipad, Industrial site, Launch facility, Launch pad, Mine, Mine 

entrance, Penstock, Pipeline, Pipeline regulation station, Power site, Railway, Railway yard, 

Reservoir, Road, Runway, Siphon, Substation, Tower, Turntable, Well, Well field 

-Bridge, Cableway, Railway, Turntable 

-Well 

-Aircraft facility, Aqueduct, Beacon, Breakwater/Jetty, Bridge, Building, Cableway, 

Canal/Ditch, Dam site, Dam/Weir, Disposal site, Flume, Helipad, Industrial site, Launch 

facility, Launch pad, Mine, Mine entrance, Penstock, Pier/Wharf, Pipeline, Pipeline regulation 

station, Power site, Railway, Railway yard, Reservoir, Road, Runway, Siphon, Substation, 

Tower, Transmission line, Tunnel, Turntable, Well, Well field 

-Bridge, Canal/Ditch, Dam/Weir, Pipeline, Road, Tunnel, Turntable 

-Mine 

-Breakwater/Jetty, Building, Pier/Wharf 

-Aircraft facility, Aqueduct, Bridge, Canal/Ditch, Dam site, Dam/Weir, Disposal site, Flume, 

Helipad, Industrial site, Launch facility, Launch pad, Penstock, Pipeline, Pipeline regulatior 

station, Power site, Railway, Railway yard, Reservoir, Road, Runway, Siphon, Substation, 

Transmission line, Tunnel, Turntable 

-Aircraft facility, Aqueduct, Beacon, Breakwater/Jetty, Bridge, Building, Cableway, 

Canal/Ditch, Dam site, Dam/Weir, Disposal site, Flume, Helipad, Industrial site, Launch 

facility, Launch pad, Mine, Mine entrance, Penstock, Pier/Wharf, Pipeline, Pipeline regulafrm 

station, Power site, Railway, Railway yard, Reservoir, Road, Runway, Siphon, Substation, 

Transmission line, Tower, Tunnel, Turntable, Well, Well field 

-Public survey area 

Appendix A-57 
Origin of survey number 

(Integer value - 01...48) - Public survey area 

Outdoor theater type 

Amphitheater -Outdoor theater 

Aqua 

Drive-in 

Ownership 

National -Land parcel 

State 

Park type 

Amusement -Park 

Botanical 

Parade ground 

Picnic area 

Playground 

Zoo 

Unspecified 

Pipeline regulation station type 

Compressor -Pipeline regulation station 

Pumping 

Valve 

Post type 

Dolphin -Post 

Piling 

Power generation method 

Nuclear -Power site 

Solar 

Unspecified 

Unknown 

Product 

Bentonite 

Brick 

Caliche 

Charcoal 

Chemical 

Chert 

Cinders 

Clay 

Coal 

Coke 

Copper 

Fuel 

Gas 

Gasoline 

Gold 

Grain 

Gravel 

Heat 

Logs 

Molasses 

Oil 

Oxygen 

Pumice 

Salt 

Sand 

Scoria 

Sewage 

Shale 

Silver 

Soda 

Soil 

-Mine 

-Kiln 

-Mine 

-Kiln 

-(Tank) 

-Mine 

-Mine 

-Mine 

-Flume, Mine, Pipeline 

-Kiln 

-Mine 

-(Tank) 

-Drilling platform, (Tank), Tank farm, Well, Well field 

-(Tank) 

-Mine 

-(Tank) 

-Mine 

-Well 

-Flume 

-(Tank) 

-Drilling platform, Flume, (Tank), Tank farm, Well, Well field 

-(Tank) 

-Mine 

-Mine, (Reservoir) 

-Mine 

-Mine 

-Pipeline 

-Mine 

-Mine 

-(Reservoir} 

-Mine 

A-58 An Enhanced Digital Line Graph Design 
-Mine 

Product (continued) 

Uranium 

Water 

Unspecified 

Unknown 

-Flume, Pipeline, Reservoir, (rank), Well 

-Flume, Mine, Pipeline, (rank), Tank farm, Well, Well Field 

-Drilling platform, Flume, Kiln, Mine, Pipeline, (Reservoir), (rank), Well, Well field 

Public survey area type 

General case -Public survey area 

Donation land claim 

Railway category 

General case -Railway 

Inclined railway 

Logging 

Rapid transit 

Unknown 

Railway gauge 

Narrow 

Standard 

Monorail 

Unknown 

Railway type 

Mainline 

Siding 

-Railway 

-Railway 

Ramp type 

Boat 

Seaplane 

-Launching ramp 

Range number 

(Numeric value with 1 alpha character (E/W)) -Public service area 

Region unit code 

(Integer value (01...21)) 

Relationship to surface 

Awash 

-Hydrologic unit 

-Rock 

Elevated above surface -Control station, Pipeline, Spot elevation, Transmission line 

Exposed at surface -Control station, Drilling platform, Pier/Wharf, Rock, Snag/Stump, Spot elevation, 

Submerged below water surface 

Under ground surface 

Reservation class 

Forest -Reservation 

General case 

Grassland 

Indian land 

Military 

Park 

Prison 

Wilderness 

Wildlife 

Unknown 

Reservation use status 

National -Reservation 

State 

Regional 

County 

Minor Civil Unit 

City 

Private 

Unknown 

Water intake/outflow, Wreck 

-Drilling platform, Pier/Wharf, Pipeline, Rock, Snag/Stump, Transmission lir~. 

Water intake/outflow, Wreck 

-Pipeline, Transmission line 

Apper~ix A-59 
Reservoir use 

Clarification -Reservoir 

Cooling 

Debris basin 

Evaporator 

Filtration bed 

Fish hatchery 

Fish pond 

Guzzler 

Industrial processing 

Industrial waste 

Percolation basin (spreading ground) 

Purification 

Retardation basin 

Settling basin 

Sewage disposal 

Storage 

Sump 

Swimming 

Unknown 

Road class 

1st 

2nd 

3rd 

4th 

5th 

Unknown 

Road type 

-Road 

General case -Road 

Overlook 

Ramp 

Rest area 

Runaway truck ramp 

Traffic circle 

Unknown 

Route designator 

(Alphanumeric identifier) 

Unspecified 

Unknown 

-Road 

Sea/Ocean type 

Reef pool 

Unspecified 

-Sea/Ocean 

Section number 

(Alphanumeric value) -Public survey area 

Signaling method 

Day beacon 

Lighted 

Radio 

Unspecified 

Unknown 

-Beacon 

Special use activity 

Dumping ground for hazardous material 

Spoil area 

Spillway elevation 

(Numeric value) 

Not applicable 

-Dam/Weir 

A-60 An Enhanced Digital Line Graph Design 

-Special use zone 
Sports site type 

Golf course -SportS tiC. 

Gun club 

Raceway 

Rodeo grounds 

Ski area 

Stadium 

Tennis court 

Stability 

Stable -~o 

Shifting 

Subregion unit code 

(Integer value (01-99)) 

Not applicable 

Surface condition 

Hard/Paved 

Not paved 

Unknown 

Survey comer type 

..JieUpad. Runway 

Arbitrary .Survey.._ 

Auxiliary meander 

Closing 

Isolated 

Land grant 

Meander 

Quarter section 

Section 

Tract 

Witness off line 

Witness on line 

Survey point type . . 

Angle point -Survey poin& 

Land grant monument 

Location monument (includes minor.a mcmumenO 

Reference monument 

Witness point 

Tank type 

Cistern -Tank 

General case 

Silo 

Storage bin 

Surge 

Tower function 

Control .. Tower 

Cooling 

Electronic 

Observation 

Mooring 

Pylon 

Support 

Water 

Unspecified 

Unknown 

Township number 

(Numeric value with 1 alpha charlct« (N/$)) -Publie aurv~y area 

Track condition/Use 

Hard/Paved-Vehicle -RaeOtr~k 

Improved/Loose-Vehiele/Animaal 

Improved-Pedestrian 

Append··~ A·61 
Track condition\Use (continued) 

Improved/Rough-Vehicle 

Unknown 

Traffic inspection facility type 

Agricultural - Traffic inspection faciliLy 

Customs 

Weigh 

Trail type 

Bicycle -Trail 

Bridle 

Marked 

Pack 

Pedestrian 

Portage 

Ski 

Snowmobile 

Winter 

Not applicable 

Unknown 

Transmission use 

Power -Transmission line 

Telegraph 

Telephone 

Unknown 

Tree category 

Deciduous -Trees 

Evergreen 

Vegetation characteristics 

Mangrove -Trees 

Unspecified 

Vegetation type 

Cranberry -Cultivated cropland 

Rice 

Unspecified 

Unknown 

Vertical control accuracy 

1st order -Control station 

2nd order 

3rd order 

3rd order or better 

Not applicable 

Wall type 

General case -Wall 

Sea 

Water characteristics 

Alkaline -Spring, (Well) 

Fresh -Lake/Pond 

Hot -Spring, (Well) 

Mineral -Spring, (Well) 

Salt -Lake/Pond, (Well) 

Sulfur -Spring 

Unspecified -Spring, (Well) 

Water intake/outflow type 

Riser -Water intake/outflow 

General case 

A-62 An Enhanced Digital Line Graph Design 
Width (meters) 

(Integer value) -Road 

Unspecified 

Windmill function 

Pump -Windmill 

Generator 

Appendix A-63 
7. ALPHABETIC LIST OF DLG-E ATTRIBUTES OF ATTRIBUTE VALUES 

Attribute: Access restrictions of Feature: Gate 

Attribute: Gate type 

Private Value: Road 

Toll 

Not applicable 

Attribute: Bathymetric datum of Feature: Contour (bathymetric) 

Attribute: Depth 

Gulf Coast low water Value: Positive numeric value) 

Lowest low water 

Mean low lake level 

Mean low water 

Mean lower low water 

Mean sea level 

Tropic lower low water 

Water surface as indicated 

Unknown 

Attribute: Call letters of Feature: Tower 

Attribute: Electronic signal 

(Alpha identifier Value: Radio 

3-4 characters) Television 

Not applicable Unspecified 

Unknown 

Attribute: Continental glaciation type of Feature: Ice mass 

Attribute: Ice mass type 

Inland ice sheet Value: Continental glacier 

Ice shelf 

Attribute: Control class of Feature: Control station 

Attribute: Horizontal control accuracy 

Class I Value: 2nd order 

Class II 3rd order 

of Feature: Control station 

Attribute: Vertical control accuracy 

Value: 1st order 

2nd order 

Attribute: Crater type of Feature: Basin 

Attribute: Basin type 

Bomb Value: Crater 

Meteoric 

Volcanic 

Attribute: Electronic signal of Feature: Tower 

Attribute: Tower function 

Microwave Value: Electronic 

Radar 

Radio 

Television 

Unspecified 

Unknown 

Attribute: Exposed portion of Feature: Wreck 

Attribute: Relationship to surface 

Mast and/or Funnel Value: Exposed at surface 

Hull and/or SuperStructure 

Attribute: Flow characteristics of Feature: Well 

Attribute: Product 

Flowing Value: Water 

Not flowing 

A·64 An Enhanced Digital Line Graph Design 
Attribute: Hydrographic category 

Dry 

Perennial 

Not applicable 

Attribute: Inclined railway type 

Cable 

Cog 

Unspecified 

Attribute: Inundation area use 

Dewatering area 

Duck pond 

Attribute: Lighthouse presence 

With lighthouse 

Without lighthouse 

Attribute: Liquid contained 

Oil 

Water 

of Feature: 

Attribute: 

Value: 

of Feature: 

Attribute: 

Value: 

of Feature: 

Attribute: 

Value: 

of Feature: 

Attribute: 

Value: 

of Feature: 

Attribute: 

Value: 

of Feature: 

Attribute: 

Value: 

Well 

Product 

Water 

Railway 

Railway category 

Inclined railway 

Inundation area 

Inundation control 

Controlled 

Beacon 

Signaling method 

Lighted 

Reservoir 

Reservoir use 

Storage 

Reservoir 

Reservoir 

Sump 

Attribute: Observation type 

Guard 

Lookout 

of Feature: 

Attribute: 

Value: 

Tower 

Tower function 

Observation 

Attribute: Owning agency 

Agricultural Research Service 

Air Force 

Army 

of Feature: 

Attribute: 

Value: 

Army (Corps of Engineers - Civil Works) 

Bonneville Power Administration 

Bureau of Indian Affairs 

Bureau of Land Management 

Bureau of Mines 

Bureau of Prisons 

Bureau of Reclamation 

Land parcel 

Ownership 

National 

Energy Research and Development Administration 

Federal Aviation Administration 

Federal Railroad Administration 

Fish and Wildlife Service 

Forest Service 

General Services Administration 

International Boundary and Water Commission, 

United States and Mexico 

National Aeronautics and Space Administration 

National Oceanic and Atmospheric Administration 

National Park Service 

Navy 

Tennessee Valley Authority 

U.S. Coast Guard 

Veterans • Administration 

Attribute: Product 

Salt 

Soda 

Unknown 

of Feature: 

Attribute: 

Value: 

Reservoir 

Reservoir use 

Evaporator 

Append'·" A-65 
Product of Feature: Tank 

Attribute: Tank type 

Chemical Value: General case 

Fuel 

Gas 

Gasoline 

Molasses 

Oil 

Oxygen 

Water 

Unspecified 

Product of Feature: Tank 

Attribute: Tank type 

Grain Value: Silo 

Unspecified 

Unknown 

Product of Feature: Tank 

Attribute: Tank type 

Grain Value: Storage bin 

Unspecified 

Unknown 

Attribute: Rock type of Feature: Barren land 

Attribute: Earth composition 

Coral Value: Rock 

Lava 

Unspecified 

Unknown 

Attribute: Route type of Feature: Road 

Attribute: Route designator 

Alternate Value: (Alphanumeric identifier) 

Business 

Bypass 

Connector 

Loop 

Spur 

Truck 

Unspecified 

Attribute: Support type of Feature: Tower 

Attribute: Tower function 

Water intake tower Value: Support 

Attribute: Stage of Feature: Lake/Pond 

Attribute: Elevation 

Average water elevation Value: (Numeric value) 

High water elevation 

Normal pool elevation 

Attribute: Text 

(Character of Feature: Beacon 

identifier) Attribute: Navigation type 

Not applicable Value: All entries 

(Character of Feature: Boundary line 

identifier) Attribute: Delineation status 

Not applicable Value: Proposed 

Protracted 

(Character of Feature: Building 

identifier) Attribute: Building class 

Not applicable Value: Class 1 

Class 2 

A-66 An Enhanced Digital Line Graph Design 
Attribute: Text (continued) 

(Character of Feature: Contour (bathymetric) 

identifier) Attribute: Bathymetric datum 

Not applicable Value: Water surface as 

indicated 

(Character of Feature: Gate 

identifier) Attribute: Gate type 

Not applicable Value: All entries 

(Character of Feature: Institutional site 

identifier) Attribute: Institutional function 

Not applicable Value: All entries 

(Character of Feature: Reservation 

identifier) Attribute: Reservation class 

Not applicable Value: All entries 

(Character of Feature: Sports site 

identifier) Attribute: Sports site type 

Not applicable Value: All entries 

(Character of Feature: Tower 

identifier) Attribute: Tower type 

Not applicable Value: All entries 

(Character of Feature: Water intake/outflow 

identifier) Attribute: Water intake/outflow type 

Not applicable Value: Riser 

Attribute: Vertical datum category of Feature: Dam/Weir 

Attribute: Spillway elevation 

Guam Mean Sea Level Value: (Numeric value) 

Datum of 1963 

Mean sea level (local) of Feature: Reservoir 

National Geodetic Vertical Attribute: Elevation 

Datum of 1929 Value: (Numeric value) 

North American Vertical 

Datum of 1988 

of Feature: Spillway 

Attribute: Elevation 

Value: (Numeric value) 

of Feature: Area to be submerged 

Attribute: Elevation 

Value: (Numeric value) 

of Feature: Lake/Pond 

Attribute: Elevation 

Value: Numeric value) 

of Feature: Stream/River 

Attribute: Elevation 

Value: (Numeric value) 

of Feature: Contour (land) 

Attribute: Elevation 

Value: (Numeric value) 

of Feature: Control station 

Attribute: Elevation 

Value: (Numeric value) 

of Feature: Spot elevation 

Attribute: Elevation 

Value: (Numeric value) 

Appendix A-67 
Attribute: Water characteristics 

Alkaline 

Hot 

Mineral 

Salt 

Unspecified 

of Feature: 

Attribute: 

Value: 

A·68 An Enhanced Digital Line Graph Design 

Well 

Product 

Water 
APPENDIX B 

DLG-E EXAMPLE DATA SET 

Section 

1. DLG-E example data set B-1 

2. Source materials B-2 

3. DLG-E feature data specifications B-4 

4. Instance count summary B-19 

5. Graph plots B-20 

6. DLG-0+ relational tables for use with DLG-E data B-22 

7. Case examples B-32 

APPENDIX B 

1. DLG-E EXAMPLE DATA SET 

OVERVIEW 

To apply the concepts discussed in the body of this report, a contrived comprehensive example DLG-E data set was 

developed. This example is intended to show the relationships between original source materials (used to construct the 

DLG-E data) and the feature/attribute definitions, delineation rules, data extraction specifications, and data representation 

rules. The example also illustrates how these specifications would contribute to the definition and building of a DLG-E 

data set. It is critical to note that a DLG-E data set, even a contrived one, cannot be built without these supporting 

specifications. The example is designed to show not only possible data content and structure for DLG-E data, but also 

the content and structure of the supporting specification documents. 

The example strives to be highly deterministic by specifying how the various preliminary rule sets are to be applied. The 

intent in any data exchange scheme is to communicate an understanding of the phenomena being represented. In the 

DLG-E case, this requires that the data user understand the feature definitions, extraction specifications, meanings of 

attributes, attribute values, digital object representations and their relationship to features, and so forth, used by the 

National Mapping Division. The ultimate goal is to have these specifications defined so precisely, that, given the same 

original source materials, two trained individuals could produce identical digital representations of a given phenomena by 

strictly adhering to all the definitions and rules. It is realized that this degree of precision may not be attainable, but 

nonetheless that should not deter the attempt to strive for this level. 

The procedures used to develop the example DLG-E data set were as follows: 

1. Building on the feature definitions and attribute lists in appendix A and the general representation rules in chapter 4, 

candidate "DLG-E feature data specifications" (including delineation, data extraction, and representation rules) wen~ 

developed for 24 selected DLG-E features in the example data set. It is important to note here that the rules 

developed in this step should be considered very preliminary; meant for illustration and experimentation purposes 

only. Actual DLG-E feature data specifications are currently being developed. 

2. A contrived graphic map and field notes were generated to illustrate possible source materials. It was decided to 

develop contrived materials (instead of using an actual real-world example) in order to include as many of the 

selected features and special cases as possible. 

3. Using the feature definitions in appendix A (plus four additional feature constructs developed for modeling purpose-s) 

and the specifications developed in step 1, the ground phenomena described in the source materials were categori?J~d 

as DLG-E feature instances. Specifically, a total of 67 feature instances of 24 DLG-E features were found. 

4. Using the representation rules from step 1, a planar graph, representative of the DLG-E feature instances found in 

step 3, was abstracted from the graphic map. This linear graph was digitized as a set of topologically integrated 

nodes, points, chains, and polygons (the DLG-E spatial objects). 

5. Each feature instance was encoded as a feature object, attributed, and related to other feature objects (if appropriat-::) 

and to the digitized spatial objects by building a set of relational tables. 

THE DLG-0+ IMPLEMENTATION 

The DLG-E example has been implemented using a specific data and file structure. It is important to remember that th.e 

same data and data model may be implemented using different structures within other environments. In fact, the plann'Xl 

distribution format for DLG-E data will be an implementation of the Spatial Data Transfer Specification (see appendix 

C), not what has been used for this example. The data structure is used here for illustration and experimentation 

purposes only. It includes the familiar DLG-3 structure (see USGS Data Users Guide 2, pages 2-3) for the implementation of the DLG-E spatial objects, attributes (location) and topological relationships. DLG-3 nodes, lines, and areas ar~ 

used to represent DLG-E nodes, chains, and polygons, respectively. (Note: a DLG-E point is implemented as a DLG--3 

"degenerate" line with node.) Feature objects, attributes, attribute values, and relationships are implemented as a set of 

relational tables. 

DLG-0+ is the file structure chosen for the DLG-E example. DLG-0+ consists of two parts: the "DLG-0" part and the 

"+" part. The DLG-0 part is simply a Digital Line Graph in Optional distribution format that holds the spatial object~ 

as "topological elements." Neither attribute codes nor text are associated with the topological elements--just coordinate 

data and topological relationships. The specifications for the "DLG-0" part are well documented in the current Standrrds 

for Digital Line Graphs (see USGS Data Users Guide 2, appendix B), and need not be repeated here. 
The "+" part of DLG-0+ consists of "flat files" associated with a DLG-0 file. In the case of our example, the "+" part 

is a set of eight relational tables, each table implemented as a single flat file. These tables serve to hold data representing the feature objects, nonspatial attribute values, and feature-to-feature and feature-to-spatial object relafons of the 

DLG-E. The following named tables have been specified for use with DLG-E data: 

1. Feature Object table 

provides a summary of the information carried in the other tables. There is one record in this table for each feature 

object. 

2. Entity Label table 

serves to store the actual entity labels (i.e., DLG-E feature tenns) associated with feature objects. Then~ is one 

record in this table for each unique entity label assigned to one or more feature objects. 

3. Attribute Definition table 

provides the means for interpreting attribute values in the Attribute Value table, and text in the Name/l'ext table. 

There is one record in this table for each unique attribute term in the data set. 

4. Relationship Definition table 

provides information for interpreting Relationship Tuple records. There is one record in this table for e:'teh unique 

type of relationship in the data set (for DLG-E data, these relationships are listed in table 4, page 5 of this circular). 

5. Attribute Value table 

serves to store the actual attribute values of attributes associated with (1) feature objects, (2) other attribute values, or 

(3) relationships. 

6. Name/Text table 

serves to store names and text strings associated with (1) feature objects, (2) attribute values, or (3) relationships. 

7. Attribute Assignment table 

provides the means by which (1) attribute values, and (2) names/text, are assigned to (a) feature objects. (b) relationships (as instanced in the Relationship Tuple records), (c) attribute assignments (as instanced in the reco ... ds of this 

table), (d) other attribute values, and (e) other feature names/text. Also, this table can associate entity hbels with 

feature objects. 

8. Relationship Tuple table 

is an object linkage table. Feature and topological objects are related to feature objects through named relationships 

(defmed in the Relationship Definition table). 

These tables will be described in more detail in Section 6. 

2. SOURCE MATERIALS 

Source materials are the actual materials used for compilation of the DLG-E data set. All information in th~ DLG-E 

must be traceable to the set of source materials. Sources may consist of graphic maps, imagery, field notes, or any other 

ancillary information containing name, boundary, or other information. For the example, a contrived graphic map and 

field classification notes were used. 

Contrived Field Classification Notes 

Entire extent of U.S. 63 on map is Alternate U.S. 63 and also is named Bishop Avenue (from Highway Department). 

The four-lane portion of Alternate U.S. 63 is also known as Memorial Drive (from local residents and l"•sinessmen). 

The entire extent of the map is in Township 6 South (from Bureau of Land Management). 

The spillway elevation for the darn on East Fork Lake is 974 feet (from County Engineer). 

The trail connecting the large part of Lane Spring State Park with the smaller south portion of the park is also part 

of the park (from Park Administrative Office). 

8·2 An Enhanced Digital Line Graph Design 
Contrived Source Map Graphic 

Appendix B-3 
3. DLG-E FEATURE DATA SPECIFICATIONS 

The feature data specifications define the domain of features that may be represented in DLG-E data. An at•empt will be 

made to extract occurrences or "instances" of these features from the source material provided. For this reason, the 

portions of the DLG-E feature data specifications related to this task are referred to as data extraction specifbations. 

Features meeting the capture conditions defmed in the data extraction specifications and discernible from the source will 

be present in the DLG-E. All remaining ground phenomena will not be represented. 

For each feature in the DLG-E feature data specification, a domain of attributes is defined. Each attribute is assigned a 

value, taken from the domain of values specified by the attribute definition authority. All attributes and attribute values 

used in the example are taken from the DLG-E features list (appendix A). 

Attributes are used to describe characteristics of features as well as attribute values. In addition, multivalued attributes 

are demonstrated. While the DLG-0+ relational table specifications allow for several rather abstract forms of attribution, 

such as attributing the assignment of an attribute or relationship, the example demonstrates only the more cormon 

applications of attributes. 

This section presents a number of the DLG-E feature data specifications used to build the DLG-E example ctata set from 

the contrived source materials in the previous section. Each DLG-E feature data specification is presented u:~mg the 

following generic template: 

DLG-E FEATURE DATA SPECIFICATION 

FEATURE - definition as documented in DLG-E domain of features. 

ATIRlBUTE/ATTRffiUTE VALUE LISTAttribute 

Value 

defmitions of attributes and values 

(those common to more than one feature are generic 

defmitions) 

DELlNEATION - (ground truth) - what the feature looks like on the ground. 

DATA EXTRACTION -

Capture Condition - criteria for determining when a feature is to be captured for inclusion in the drta base. 

This is independent of source. 

Source Interpretation Guidelines - criteria for extracting ground truth, for those situations that are a.t""'biguous, 

from various sources (image, field, graphic, DLG-3). 

Valid Attributes - which attributes are valid for a given scale. 

REPRESENTATION RULESComposition Rules - under these conditions, feature has these relationships (allowed relationships rn'-'y not 

always occur). 

If (feature) is (condition), (feature) is composed of/part of.. .. , bounded by/bounds .... , inflows to/outfhws from .... , 

connected to, and vertically related to .... 

Delimiting Rules - definition of feature instance based on global rules. 

Special Conditions - specific definition rules which are peculiar to a specific feature. 

Vector Model Consideration - TBR 

On the next several pages, the very preliminary DLG-E feature specifications for the following DLG-E fean·..-es are 

presented: stream/river, spring, road, underpass, junction, shoreline, reservation, boundary line, and ridge. 

B-4 An Enhanced Digital Line Graph Design 
STREAM/RIVER- A body of flowing water. 

ATTRmUTE/ATTRmUTE VALUE USTDelineation status -

Apparent 

Definite 

Not applicable 

Directional status -

Alternating 

Bidirectional 

Not applicable 

One way 

Unknown 

Unspecified 

Elevation -

(Numeric value) 

The level of confidence with which a featme can be 

defined. 

Conditions prevent the feature from being confide:'ltly 

defmed because of obscuring vegetation or shadovrs. 

Conditions permit the feature to be confidently de~ed. 

The state of movement along the feature. 

Movement occurs in both directions, however onl~· one 

way at a time. 

Movement occurs in both directions simultaneoust·. 

Movement occurs in only one direction. 

The vertical distance of a feature above a given datum. 

Increment: 0.1 feet 

-->Vertical Datum Category The base elevation used as a reference from whic."' to 

reckon heights or depths. 

Mean Sea Level (Local) 

The average height of the surface of the sea for fll 

stages of the tide, usually determined by averagin,'! 

height readings observed hourly over a 19-year }X'riod. 

National Geodetic Vertical Datum of 1929 

A fixed reference adopted as a standard geodetic datum 

for heights, derived for land surveys from a geucral 

adjustment of first order land nets of both the Un'ted 

States and Canada. 

North American Vertical Datum of 1988 

As of 2/89 this proposed vertical datum has not t'~n 

defmed. 

-->Stage The height of water surface above the vertical datwn. 

Unknown 

Not applicable 

Hydrographic category -

Intermittent 

Perennial 

Unknown 

Hydrographic form -

Braided 

Not braided 

Normal Pool Elevation 

The normal stage of water that prevails for most of the 

year for a controlled body of water. 

High water elevation 

A stage of water that prevails when the feature is at or 

near capacity. 

The portion of the year the feature contains water. 

Contains water for only part of the year, but mon than 

just after rainstorms and at snowmelt (see feature 

WASH). 

Contains water throughout the year, except for 

infrequent periods of severe drought. 

The pattern of channels. 

Feature has a stream course which is not filled at 

normal flow, and that subdivides into interlacing 

channels. 

Feature has a stream course that is filled at normal flow 

and that does not subdivide into interlacing chanr~ls. 

Appendix B-5 
DELINEATION • 

Name· 

(Character identifier) 

Not applicable 

Unknown 

The proper name, specific term, or express;()Jl by which 

the feature is known. 

The upper limit of a stream is determined to be the point at which the feature fust becorr·~s evident as 

a channel. 

The limits of a perennial stream are determined to be the height on the banks when water is at 

average water elevation. 

The limits of an intermittent stream are determined to be the height of the banks when w~ter is at high 

water. 

The lower limit of areal streams entering into bays, estuaries, gulfs, oceans, or seas is defined at the 

place where the stream reaches a width of 1 nautical mile with no further constrictions, if the land and 

water do not otherwise make the division obvious. 

DATA EXTRACTION at 1:24,000 scale . 

Capture Condition • 

All streams are captured to within 0.5" of saddles or divides. 

Capture all tributaries with a length of 1.25" or longer. 

Capture additional tributaries less than 1.25" in length if needed for contour portrayal. 

If overedge source is not available to make length determination, all streams intersecting cell boundaries will be captured, regardless of length. 

Capture all streams that are connected to springs or ponds. 

Capture only the above-ground portion of streams. See feature SINK for those streams which 

disappear in karst areas. 

Capture a representative pattern for braided streams: always collect perennial streams, alvrays collect 

double·line streams, always collect streams which form bounding limits. 

Source Interpretation Guidelines • 

All sources · 

If a stream/river is controlled by locks, a normal pool elevation is required. Water surface elevations 

are given to the nearest whole foot. Artificial lakes formed by water impounded by a da--n are 

considered under the feature LAKE/POND. 

Dry washes, arroyos, dry gulches, and ephemeral streams are considered under the feature WASH. 

ImageIf image shows a lower than average water elevation, look for evidence of water marks, <l.elineate at 

that level. 

If image shows higher than average water elevation, the mean water level must be obtain~ from 

ancillary sources. 

GraphicApproximate, indefinite, and unsurveyed streams/rivers have a delineation status of "appar~nt" 

Braided stream • capture all channels. 

DLG-3-

Approximate, indefmite, and unsurveyed streams/rivers have a delineation status of "appannt" 

Valid Attributes -

All attributes are valid. 

B·6 An Enhanced Digital Line Graph Design 
REPRESENTATION RULES at 1:24,000 scaleComposition Rules -

If stream is linear, stream is composed of sequenced, directed chain(s). 

If stream is areal, stream is composed of area bounded by shoreline(s), with inflow to/outflow from 

junction, vertically related to other feature. 

Delimiting Rules - delimit instance using rules for network links. 

Special Conditions -

The stream representation will change from the linear representation to areal representation 

when the stream width becomes greater than 0.02". 

To accommodate variations in stream width: 

if stream (area) becomes 

less than 0.02" but greater than 0.01" for greater than 2.64", represent feature as an 

area 

less than 0.02" but greater than 0.01" for less than 2.64", represent feature as a li"'e 

less than 0.01" regardless of distance, represent as a line 

if stream (line) becomes 

greater than 0.02" but less than 0.03" for less than 2.64", represent as a line 

greater than 0.02" but less than 0.03" for greater than 2.64", represent as an area 

greater than 0.03" regardless of distance, represent as an area. 

Transitional tapering from linear representation to areal representation will take place over a 

distance of 0.15" prior to the 0.02" width requirement, and vice versa. 
SPRING -A place where water issues from the ground naturally. 

ATTRIBUTE/ATTRIBUTE VALUE LISTDELINEATION -

Angle of orientation -

Name0 - 359 degrees 

Not applicable 

(Character identifier) 

Not applicable 

Unknown 

Water characteristics -

Alkaline 

Hot 

Sulfur 

Unspecified 

The angular measurement of a feature, calrulated from 

true north (0 degrees), clockwise to the mfjor axis of 

the feature. 

Increment: 1 degree 

The proper name, specific term, or express~<m by which 

the feature is known. 

The distinctive properties of the water. 

Water shows evidence of alkali salts. 

Water temperature is higher than that of the human 

body (98 degrees). 

Water shows evidence of enough hydrogen sulfide to 

smell and/or taste. 

A spring is an area, bounded by the edges of the place where water issues from the groui'd. 

DATA EXTRACTION at 1:24,000 scaleCapture Condition -

All required 

Source Interpretation Guidelines -

All sources -

The major axis for angle of orientation on isolated springs is along its downward slope. 

Springs located within stream/river or lake/pond do not require angle of orientation. 

DLG-3-

If the DLG-3 descriptive code is 050.0615 (mineral or hot), the compiler must reference the source 

graphic to determine the attribute value. 

Field -

Evidence of alkali salts is determined by observation of alkali residue around the spring. 

Valid Attributes -

All attributes are valid. 

REPRESENTATION RULES at 1:24,000 scaleComposition Rules -

If spring is located within a stream, spring is composed of a node. 

If spring is not located within a stream, spring is composed of a point. 

Delimiting Rules -

Special Conditions -

B-8 An Enhanced Digital Line Graph Design 
UNDERPASS -The occurrence of an intersection of two feature instances with a vertical relationship. 

ATTRIBUTE/ATTRIBUTE VALUE UST- None 

DELINEATION- Not applicable 

DATA EXTRACTION at 1:24,000 scaleCapture Condition -

Use when features carrying traffic or having flow pass under other features and the relative verticRI 

information cannot be determined by other information. 

Source Interpretation Guidelines -

Not applicable 

Valid Attributes -

Not applicable 

REPRESENTATION RULES at 1:24,000 scale -

Composition Rules -

When the overpassing/underpassing features are both chains, and not coincident, underpass is composed 

of a node, vertically related to other features. 

When the overpassing/underpassing features are both chains, and are coincident, underpass is composed 

of chains, vertically related to other features. 

When one of the overpassing/underpassing features is a chain and the other is an area, underpass is 

composed of a chain, vertically related to other features. 

When the overpassing/underpassing features are both areas, underpass is composed of an area, 

vertically related to other features. 

Delimiting Rules -

Special Conditions -

Only two features may be vertically related with the feature "underpass." In the case of three 

or more features overpassing each other at the same spatial location, only vertically adjar~ent 

features shall be referenced in the "underpass" feature. Thus, a triple overpass shall gen~ate 

two underpass instances - one for the top and middle features and another for the middlft and 

bottom features. 

Appendix 8-8 
JUNCTION - The occurrence of an intersection of two areal features having flow. 

ATIRIBUTE/ATIRIBUTE VALUE UST- None 

DELINEATION- Not applicable 

DATA EXTRACTION at 1:24,000 scale -

Capture Condition -

Use when one areal network link with flow joins another or when an areal network link wi .. h flow 

intersects the cell boundary. 

Source Interpretation Guidelines -

Not applicable 

Valid Attributes -

Not applicable 

REPRESENTATION RULES at 1:24,000 scale -

Composition Rules -

Junction is composed of chains, with inflow to/outflow from other areal features. 

Delimiting Rules -

Special Conditions -

8·10 An Enhanced Digital Line Graph Design 
SHORELINE - A naturally occurring line of contact between a body of water and land. 

AITRIBUTE/AITRIBUTE VALUE LISTDELINEATION -

Delineation status -

Apparent 

Definite 

The level of confidence with which a feature can be 

defined. 

Conditions prevent the feature from being confidently 

defined because of obscuring vegetation or shadows. 

Conditions permit the feature to be confidently define·\. 

The definite shoreline is the line of contact between water and land. The apparent shoreline in tidal 

areas is the seaward edge of marine vegetation where that limit would reasonably appear as the 

shoreline to the mariner. The apparent shoreline for inland areas is the estimated line of contact 

between water and land. 

DATA EXTRACTION at 1:24,000 ScaleCapture Condition -

Capture all natural shorelines bounding other features that meet minimum capture conditions. 

Source Interpretation Guidelines -

Image -The position of a shoreline is interpreted at a water level defined by the feature to be 

bounded. 

Graphic - All shorelines are captured as shown on graphic. Shorelines shown as indefinite, approximate, or unsurveyed will be captured as with a delineation status of "apparent." 

DLG-3 -The following attributes will convert to the DLO-E feature shoreline: 

050 0200 Shoreline - collect as definite shoreline 

050 0203 Indefinite Shoreline - collect as apparent shoreline 

050 0207 Apparent Shoreline - collect as apparent shoreline 

050 0201 Manmade Shoreline becomes a feature in DLG-E. 

Valid Attributes -

All attributes are valid. 

REPRESENTATION RULES at 1:24,000 scale -

Composition Rules - shoreline is composed of chain(s), bounds lake/pond, sea/ocean, stream/river, areas 

to be submerged, bay/estuary{mlet, inundation area. 

Delimiting Rules - Delimit instances using the rules for network links. 

Special Conditions -

Appendl:~ 8·11 
RESERVATION - Bounded land set aside for a particular purpose, generally having certain use restrictions. 

AITRillUTE/ATTRIBUTE VALUE USTDELINEATION -

Name-

(Character identifier) 

Not applicable 

Unknown 

Reservation class -

Forest 

General case 

Grassland 

Indian land 

Military 

Park 

Prison 

Wilderness 

Wildlife 

Unknown 

Reservation administrative status -

National 

State 

Regional 

County 

City 

Unknown 

The proper name, specific term, or express-\on by which 

the feature is known. 

The primary use associated with the reservation. 

Area primarily for the management of fore.~t resources. 

Area primarily for the management of nati·re grasses. 

As defined by Bureau of Indian Affairs. 

Area primarily for military activities and P''rposes. 

Area primarily for preservation of a cultural or natural 

resource. 

Area for housing persons convicted or accnsed of 

crimes. 

Area virtually unsettled and uncultivated (r~ttural); 

includes areas designated by an administra .. ive group as 

wilderness, primitive, wild and scenic, or rimilar 

designation. 

Area primarily for wildlife management or preservation; 

includes the following areas: conservation, game, 

hunting/fishing, preserve, or other area witi "wildlife" in 

name. 

Managing authority. 

Group of State, county, and/or city govem'1lents. 

The reservation area is delineated by the boundary line that surrounds the reservation. TJ·~ area is 

usually defined by law, proclamation, or ownership. 

DATA EXTRACTION at 1:24,000 scale -

Capture Condition -

Capture all reservations. 

Nonproclaimed inholdings greater than .05" in the shortest dimension should be excluded from the 

reservation. 

Source Interpretation Guidelines -

Graphic - capture limits (boundaries) of area as shown on graphic. Update as current de.~~ription 

indicates. 

DLG-3 - capture area attribute codes: 

090 0103 through 0111, 0129 through 0134, 0150 - compiler must reference ft·P. source 

graphic to determine appropriate reservation class. 

090 0420 (cemetery) with coincidence code 209 0009 - this indicates National r.emetery. 

B·12 An Enhanced Digital Line Graph Design 
Field - contact administrative group and obtain legal description. When bounded by a road, detenni"'e 

whether the reservation extends to the center of the road or to the edge of the road. The description 

should be used to verify other sources. 

Valid Attributes -

all attributes are valid. 

REPRESENTATION RULES at 1:24,000 scaleComposition Rules -

Reservation is composed of area, bounded by boundary line. 

Delimiting Rules -

Special Conditions -

Appendl"" B-13 
BOUNDARY LINE -A separation between divisions of current or past significance. 

ATIRIBUTE/ATTRffiUTE VALUE LISTDELINEATION -

Delineation status -

NameApproximate/Indefinite 

Definite 

Disputed 

Historical 

Protracted 

(Character identifier) 

Not applicable 

Unknown 

The level of confidence with which a feature can be 

defined. 

Conditions prevent the feature from being located to 

meet NMAS. 

Conditions permit the feature to be confider~ly defined. 

The location of State, county or national rer~~ation 

boundary is in controversy because of confl~~ting or 

unclear legal definitions. 

The location can be confidently defined but has lost its 

original significance. 

Boundary line is extended from or fit betw~en established surveyed points pending actual growl'i survey. 

The proper name, specific term, or expressi "D by which 

a particular geographic entity is known. 

Boundary lines are delineated as defined by law or proclamation. 

DATA EXTRACTION at 1:24,000 scale -

Capture Condition -

Capture all established civil boundaries. 

Source Interpretation Guidelines -

GraphicInterpret as shown and adjust to legal description if required. 

DLG-3-

Capture following line attribute codes: 

090.0201 becomes Indefinite/Approximate. 

090.0202 becomes Disputed. 

090.0203 becomes Historical. 

If line in DLG-3 boundary category does not carry any of the above descriptive codes, atTribute value 

becomes Definite. 

300.0202 becomes Protracted. 

300.0205 becomes Definite. 

Field -

Obtain legal descriptions. Determine whether boundary lines are coincident with centerlines or edges 

of features, such as roads, railroads, and streams. 

Valid Attributes -

All attributes are valid. 

REPRESENTATION RULES at 1:24,000 scale -

Composition Rules -

Boundary line is composed of ordered chains, bounds other features. 

Delimiting Rules -

Special Conditions -

B-14 An Enhanced Digital Line Graph Design 
RIDGE- A long and narrow upland with steep sides. 

ATTRffiUTE/ATTRIBUTE VALUE UST -

Name-

(Character identifier) 

DELINEATIONThe proper name, specific term, or expression by whbh 

the feature is known. 

The limits of the ridge are defined by the break in slope between the steep sides of the feature and the 

relatively flat terrain at the base of the feature. 

DATA EXTRACTION at 1:24,000 scale -

Capture Condition -

All ridges and associated generics contained in the Geographic Names Information System Phase ll 

listing are required. 

Source Interpretation Guidelines -

Valid Attributes -

All attributes are valid. 

REPRESENTATION RULES at 1:24,000 scale -

Composition Rules -

A ridge is composed of an area. 

Delimiting Rules -

Special Conditions -

Appendlr 8·15 
ROAD - An open way for the passage of vehicles. 

AITRIBUTE/ATTRIBUTE VALUE LIST -

Access restrictions -

Private 

Restricted 

Toll 

Unknown 

Unspecified 

Directional status -

Alternating 

Bidirectional 

Not applicable 

One way 

Unknown 

Unspecified 

Median category -

NameWith median 

Without median 

(Character identifier) 

Not applicable 

Unknown 

Number of lanes or tracks -

(Integer value) 

Unspecified 

Unknown 

Operational status -

Abandoned 

Operational 

Proposed 

Under construction 

Unknown 

Road class -

1st 

2nd 

3rd 

B·16 An Enhanced Digital Line Graph Design 

The constraints on use. 

Maintained by private funds and not open tc the public. 

Designated for official use only. 

Controlled by payment of fee for travel. 

The state of movement along the feature. 

Movement occurs in both directions, howevn only one 

way at a time. 

Movement occurs in both directions simultar~usly. 

Movement occurs in only one direction. 

The existence of a median. 

Curbs or median strips separate opposing tnffic lanes. 

Traffic lanes are not separated by curbs or I""edian 

strips. 

The proper name, specific term, or expresskn by which 

the feature is known. 

The state or condition. 

Intact but not maintained or intended for use. 

Usable and intended for use. 

Planned in detail, but construction not starte~. 

Construction started, but not complete. 

The classification of roads based on design, weatherability, governmental designation, and the Department of 

Transportation functional classification system. 

Hard-surface highways including interstate a"'d U.S. 

numbered highways (including alternates, pt.mary State 

routes, and all controlled access highways). 

Hard-surface highways including secondary State routes, 

primary county routes, and other highways that connect 

principal cities and towns, and link these pl!!Ces with 

the primary highway system. 

Hard-surface highways not included in a hirher class 

and improved, loose-surface roads passable in all kinds 

of weather. These roads are adjuncts to the. primary 

and secondary highway systems. Also inclrried are 

important private roads such as main loggin~ or 

industrial roads which serve as connecting r"'lks to the 

regular road network. 
DELINEATION -

4th 

5th 

Unknown 

Road typeGeneral case 

Overlook 

Ramp 

Rest area 

Runaway truck ramp 

Traffic circle 

Unknown 

Route designator -

Width-

(Alphanumeric identifier) 

Alternate 

Business 

Bypass 

Connector 

Loop 

Spur 

Truck 

Unspecified 

Unspecified 

Unknown 

(Integer value) 

Unspecified 

Unknown 

Improved, loose-surface roads passable only in fair 

weather. 

Unimproved roads passable only with four-wheel-drh·~ 

vehicles. Included are one-lane roads on levees, and 

maintenance roads along transmission and other simi' ''\I 

features. 

The purpose or function. 

Common use. 

A pull-off area designated as scenic, having definite 

entrance and exit points that are separated from the 

roadway. 

An inclined road connecting roads of differing levelr. 

An access road to service facilities such as service 

stations, weigh stations, comfort stations, restaurants, 

and parking areas. 

A short inclined road constructed of unconsolidated 

material that exits gradually from and runs adjacent to 

the right lane of a descending highway, for stopping 

runaway trucks. 

A junction of roads that forms a circle around whicl, 

traffic moves in one direction. 

The official alphanumeric identifier. 

The span of the feature perpendicular to traffic flow. 

A road is delineated by the edge of all traffic lanes, excluding the shoulders. 

DATA EXTRACTION at 1:24,000 scale -

Capture Condition -

All roads are captured, excluding driveways that are less than .25". 

Appendix 8·17 
Source Interpretation Guidelines -

All sources -

Hard-surface construction is generally concrete, asphaltic concrete, or bitwninous macadam. Surfaces 

are waterproof. Minimum maintenance is required. 

Improved, loose-surface construction is on light foundation and is usually gravel or stone surface, or of 

some stable material, such as selected sand-clay, treated oil gravel, or light tar-bound macac'1.'Ull. The 

roads are generally drained and graded, but the surface is not waterproof. Periodic mainterrmce is 

required. 

Unimproved-surface construction is usually stabilized soil, sand-clay, or disintegrated rock with poor or 

no foundation. The road is sometimes drained or graded. If the roads are maintained at al', continual 

maintenance is required. 

Only class 3 roads are designated to have an access restriction of "private." 

Route designators are captured for Interstate highways, U.S. numbered highways, and State highways. 

Names are captured for expressways and turnpikes, historical names required to preserve continuity of 

a feature, all streets in urban areas, and well-known or posted roads in rural areas. 

ImageFor dual highways less than or equal to .035" in overall width, capture the median centerlin';'\, with 

median category value of "with median" and width with a value for the extent of the road including 

the median. 

For dual highways greater than .035" in overall width, capture the centerline of each roadWP', with 

median category value of "with median" and width with a value for the width of each roadPay. 

REPRESENTATION RULES at 1:24,000 scale -

Composition Rules -

If width is less than or equal to .05", road is composed of ordered chain(s), vertically related to other 

feature. 

If width is greater than .05", road is composed of area, connected to junction, with inflow t<l/outflow 

from junction, vertically related to other feature. 

Delimiting Rules - Delimit instances using rules for network links. 

Special Conditions -

B-18 An Enhanced Digital Line Graph Design 
4. INSTANCE COUNT SUMMARY 

For the example DLG-E feature data specification, 24 features were selected from the 202 features defined in the DLG-E 

features list (and four additional modeling constructs). Note: only nine of the feature data specifications are actually 

documented in this appendix. A total of 67 feature instances (of the 24 features) were discernible from the source 

material provided and met the capture conditions specified in the DLG-E feature data specification. The instance cowu 

summary details how many instances occurred for each feature and the number of attributes for each feature. 

Number of Feature Number of 

Feature Instances (A) Attributes (B) AxB 

Named Feature 7 1 7 

Road 15 7 105 

Railway 4 4 

Stream 8 3 24 

Lake 2 2 

Spring 1 2 2 

Dam 1 3 3 

Shoreline 2 1 2 

Junction 1 0 0 

Nation 1 1 1 

State Territory 1 2 2 

County 2 2 4 

Domain 1 0 0 

Public Survey Area 2 3 6 

Ridge 1 1 1 

Cemetery 1 1 1 

Institutional Site 1 2 2 

Reservation 3 3 9 

Bridge 1 4 4 

Building 5 2 10 

Underpass 4 0 0 

Trail 1 3 3 

Ford 1 1 1 

Boundary Line 5 1 5 

TOTALS 67 instances 198 

(counted) computed 

attribute 

values 

Appendix 8·19 
5. GRAPH PLOTS 

Plots of the resultant DLG-0 are provided to identify the spatial objects referenced by the Relationship Tuple Table. For 

clarity, two plots were produced. Chain (line) and point ID's are labeled on the first plot. Area ill's are lab~led on the 

second plot. Arrows on the chain plot indicate the direction of each chain. 

Chains and Points with ID Numbers 

HI 79 

83 

6 

5 

86 

10 

11 18 

40 

88 

44 

92 

69 

111 

105 103 

110 106 104 

--Chains •- Points 

Labeled Chains and Points 

B-20 An Enhanced Digital Une Graph Design 
Areas with ID Numbers 

. 4 • 2 

I 6 

. 8 

1 0 

• 11 

• 2 2 

• 2 7 

• 3 6 

• 4 1 

Appendix 8·21 
6. DLG-0+ RELATIONAL TABLES FOR USE WITH DLG-E DATA 

Explanations of the eight relational tables designed for use with DLG-E data are presented. Definitions of tt~ fields 

(domains) of the tables are given, distinguishing key fields, foreign ID fields, and "other" fields. The information 

provided in this section is necessary for the reader to understand the case examples which follow. 

This section presents the design of a set of DLG-0+ tables or "flat files" for use in implementing DLG-E features, 

nonspatial (nonlocational) attributes and values, and nontopological relationships. In a DLG-0+ data set, DLG-E data are 

separated into spatial and nonspatial components. A DLG-0 file, without attributes or text, carries the spatia1 

information. DLG-0+ flat files carry the nonspatial information. This organization is much like that employ~d by a 

number of currently available commercial geographic information systems. ARC/INFO, for example, stores s:""atial data in 

ARC files and nonspatial data in related INFO (a commercial relational data base management system) files. 

The following named tables have been specified for use with DLG-E data: 

1. Feature Object table 

2. Entity Label table 

3. Attribute Definition table 

4. Relationship Defmition table 

5. Attribute Value table 

6. Name/fext table 

7. Attribute Assignment table 

8. Relationship Tuple table 

THE USE AND STRUCTURE OF "OBJECT" KEYS AND FOREIGN IDENTIFIERS 

In a DLG-0 file, each topological object has an associated key by which it may be uniquely identified and referenced. 

In the tables presented below, each feature object instance, attribute value (including name/text) instance (or set--see 

below), entity label, attribute value assignment, and relationship tuple instance (or set) also has such a key. When 

referenced from other records, these keys are termed "foreign identifiers" (foreign ID). In the tables, a given foreign ID 

field may reference more than one type of object, attribute value, or relationship instance. For this reason, tl ~ structure 

of these keys and foreign ID's must be identical. 

Each object key/foreign ID begins with a single letter indicating object type, followed by a five-digit integer unique 

within that object type and data set. The following letters, used throughout the remainder of this section to refer to 

object types, tables, and types of foreign identifiers, indicate object type: 

"A" indicates an Area (polygon), 

"C" indicates a Chain, 

"N" indicates a Node, 

"P" indicates a Point, 

"F" indicates a Feature object, 

"E" indicates an Entity label, 

"V" indicates an Attribute value, 

''T" indicates a N ame/fext, 

"S" indicates an Attribute assignment, and 

"R" indicates a Relationship tuple. 

The first four object types are the topological objects in the DLG-0 file; the five digit integers identifying tl';\Se objects 

are the same as the "element internal ID" numbers in the DLG-0 Area, Line, and Node Identification records. The 

remaining six "object" types are represented by the records of the tables of the same name. Note that attribnte labels and 

relationship labels also have unique keys (in the Attribute Definition and Relationship Defmition tables, respE'.ctively), but 

these are referenced from specific foreign ID fields reserved just for them (in the V, T, and R tables). Thes~ keys 

therefore need not have the same structure as the "object" keys. 

MINIMUM FOUR-TABLE SET PLUS FOUR 

A minimum set of tables, designed to carry all the nonspatial components of the DLG-E model could consist of just four 

tables. Two tables, (1) Attribute Definition and (2) Relationship Definition, carry definitional data, and two tables, 

(3) Attribute Value and (4) Relationship Tuple, carry instance data. The Attribute Definition table would carry a record 

for each unique attribute label (term) in the data set (with special records for "Entity Label" and "Comment"). The 

Attribute Value table carries the actual attribute values (as well as entity labels, names, and comment text). In order to 

interpret the attribute values correctly, each Attribute Value record carries the foreign ID of the appropriate Attribute 

B-22 An Enhanced Digital Line Graph Design 
Definition record. Likewise, the Relationship Definition table carries a record for each unique relationship in the data sPot 

(with a special record for an "Attributed by" relationship). The Relationship Tuple table carries the actual pair-wise 

object-to-object instances of these relationships. 

For efficiency (e.g., DLG-0+ must implement these tables as fixed-length fields and records) and other reasons, additior.lll. 

tables are developed here. To the minimum four, four tables are added: (5) Entity Label, (6) Name{fext, (7) Attribute 

Assignment, and (8) Feature Object. No new information is handled by these tables, but rather information which migh<: 

have been carried in the minimum table set is separated out and placed in the additional tables. The Entity Label and 

Name{fext tables contain, in essence, special case records from the Attribute Value table. The Attribute Assignment taHe 

contains all the "Attributed by" records from the Relationship Tuple table. The Feature Object table summarizes certain 

feature object data. 

The reason for adding the Name{fext table is for storage efficiency. When implementing tables within a fued-length 

record environment, the length of the Value field in Attribute Value table would have to be set to the longest name or 

text string value. Instead we will remove those names and long text strings and keep the Value field only large enougt, 

to handle single numbers and short alphanumeric codes (e.g., 24 bytes). The Name{fext table has the identical structurPas the Attribute Value table, but with a much larger value field for handling names and other long textual attribute 

values. 

The reason for adding the Entity Label, Attribute Assignment, and Feature Object tables is for clarity. To have a more 

explicit structural equivalence to components of the DLG-E data model and the entity/attribute feature definition model, 

Entity Labels are distinguished from Attributes (by the Entity Label table), and Entities and Attributes are distinguished 

from Relationships (by the Attribute Assignment table). And finally the Feature Object table provides feature objects with 

their own "starting place" access table with records keyed by feature object ID (without this table, feature objects would 

be the only "objects" without a table explicitly keyed to their !D's). 

A DESCRIPTION OF FOLLOWING SUBSECTIONS 

The remainder of this section consists of three subsections. 

Full Descriptions of DLG-0+ Tables for Use with DLG-E: 

Five numbered items describe each of the eight tables: 

1. Name of Table; 

2. Purpose - a brief summary description; 

3. Key field: 

Name - always the name of the table followed by "Key," 

Unique? - "YES" or "NO" (if "NO" (for Attribute Value, Name{fext, Attribute Assignment, and Relationship 

Tuple tables), then a secondary field named "Order Sequence Number" is concatenated with the key field to 

provide a unique key for each record), and 

Construction - "[object type letter]" + 5 digits, except for the Attribute Definition and Relationship Definition 

tables; 

4. Foreign ID field(s) - for each foreign ID field, its full name is given followed by a description, including purpose 

and what records (by object type if appropriate) may be referenced; and 

5. Other fields - for each of the remaining fields, its full name is given followed by a description, including purpose 

and a definition of possible data item contents. 

Table/Field Summary: 

For each table, a FORTRAN record format is given (these are what have been used for this example only--other 

formats may be developed for more voluminous datasets). Then for each field, its full name is equated to a short 

three- to five-character mnemonic and its byte (column) position within the record. This summary is meant to 

provide a user with the means to read individual records in the case examples (section B.7) and to allow short fie~d 

names to be used in discussions which follow (and in programming languages). 

Foreign ID's Pointing to "Object" Keys: 

This subsection presents a discussion of how the records of the various DLG-0+ tables interrelate through the use: of 

foreign ill's. Specifically, for each table (except the Entity Label, Attribute Definition, and Relationship Definition 

tables, which do not have foreign ID fields), each foreign ID field is related to the key field(s) of other table records 

to which the foreign ID may refer. 

Appendix r ·~3 
Full Descriptions of DLG-0+ Tables for Use with DLG-E 

1. Name of Table: Feature Object 

2. Purpose: This table provides a summary of the information carried in the other tables about each featm·~ object. 

3. Key field name: Feature Object Key 

Unique?: YES. 

Construction: "F" + 5 digits. 

4. Foreign ID field(s): 

Primary Entity Label - this field carries the foreign ID of the primary entity label (in the Entity Label ti'\ble) of this 

object. Usually one and only one entity label is assigned a given feature object. If no entity label is assigned 

to a feature object, this field shall be null. If more than one entity label is assigned a given featur~ object, one 

of the labels must be chosen as the "primary" label. 

5. Other fields: 

(a) Dimensionality -- indicates the spatial dimension of the feature object; must be one of the following characters: 

"0" (point features), 

"1" (linear features), 

"2" (areal features), 

"M" (mixed), or 

"U" (unknown). 

(b) Composition -- indicates the type of objects which comprise this feature object. This is defined by the object 

type code of those objects recorded as second tuple elements in Relationship Tuple records with the defmed 

relationship being "Composed of' and this feature object as first tuple element. In addition to the type codes F, 

A, P, N, and C, the contents of this field may be: 

"S" to indicate a mixed spatial object (A, P, N, and C type objects) composition, 

"M" to indicate a mixed feature and spatial object composition (F plus A, P, N, and/or C type objects), or 

"U" for unknown composition. 

(c) Contiguous? -- indicates whether the objects which comprise this feature are spatially contiguous or disjoint. 

The contents of this field may be "Y" (yes, they are contiguous), "N" (no), or "U" (unknown). 

(d) Number of Unique Relationships -- this is defined as the number of unique Relationship Tuple Key~ of all 

Relationship Tuple records with this feature object as the first tuple element. 

(e) Number of Relationship Tuple records -- the actual number of Relationship Tuple records with this featme 

object as the first tuple element. 

(f) Number of Entity Labels Assigned -- indicated by the number (normally one) of Attribute Assignm~nt records 

with an entity label assigned to this feature object. 

(g) Number of Attribute Values (or Value Sets) Assigned -- indicated by the number of Attribute Assignment 

records with Attribute Value foreign ill's (one ID may reference one Attribute Value record or a s"'.t of records 

with the same key representing an attribute value set) assigned to this feature object. 

(h) Number of Name{fext Strings (or String Sets) Assigned -- indicated by the number of Attribute Assignment 

records with Name/fext foreign ID's (one ID may reference one Name/Text record or a set of records with the 

same key representing a name/text string set) assigned to this feature object 

=============================================== 

1. Name of Table: Entity Label 

2. Purpose: This table serves to store the actual entity labels associated with feature objects. There is on~ record in 

this table for each unique entity label assigned to one or more of featme objects. 

8·24 An Enhanced Digital Line Graph Design 
3. Key field name: Entity Label Key 

Unique?: YES--as opposed to Attribute Value records, each of which may carry an individual value of a multivall·~d 

attribute value set, Entity Label records must always be referenced individually. 

Construction: "E" + 5 digits. 

4. Foreign ID field: none. 

5. Other fields: 

(a) Entity Label -- the actual alphanumeric text which is a feature/entity term (e.g., "Road"). 

(b) Definition Authority - Source of the definition for this feature/entity term (e.g., "USGS/NMD, DLG-E"). 

1. Name of Table: Attribute Definition 

2. Purpose: This table provides the means for interpreting attribute values in the Attribute Value and Name{fext tabhs. 

3. Key field name: Attribute Defmition Key. 

Unique: YES. 

Construction: "AD" + 4 digits. 

4. Foreign ID field(s): none. 

5. Other fields: 

(a) Attribute Label - Name given to this attribute (e.g., "Width"). 

Note that if the minimum table set were used, "Entity Label" would be a special reserved attribute label 

indicating that the Attribute Value field is to be read as a feature/entity term; an Entity Label table, if present. 

obviates the need for this special attribute label. 

(b) Attribute Definition Authority - Source of the definition for this attribute (e.g., "USGS/NMD, DLG-E"). 

(c) Attribute Value Format - How to read the values assigned to this attribute; must be one of the following (Not~: 

coding should follow IS0-6093, etc. standards): 

A ("printable" ASCIT characters) 

I (implicit-point--integer), 

R (explicit-point unsealed--real without exponent), 

S (explicit-point scaled--real with exponent), 

B (bitfield data), or 

C (character-mode bitfield). 

(d) Attribute Value Measurement Units (e.g., "meters") - this field may be null for nonnumeric attribute values. 

Further Comments: 

The Attribute Definition table will carry one record for each defined nonlocational attribute used in the DLG-E da<:a 

set. The meaning of the actual labels (in the Attribute Label field) and values (in the Attribute Value and 

Name/fext tables--see below) are defined by some authority (e.g., USGS/NMD, DLG-E), but this meaning is not 

repeated here. The Attribute Authority field is meant as a reference for such definition. 

Note also that a given attribute label, including "Entity Label," is not necessarily unique. Different authorities may 

be used to define feature/entity terms or different meanings to attributes of the same name. The combination of 

attribute label and attribute authority is what makes an attribute unique. 

================================--============== 

1. Name of Table: Relationship Definition 

2. Purpose: provides information for interpreting Relationship Tuple records. 

3. Key field name: Relationship Definition Key 

Unique?: yes. Construction: "RD" + 2 digits. 

Appendix r·?.S 
4. Foreign ID field(s): none. 

5. Other fields: 

(a) Relationship Label - Name given to this relationship (e.g., "Composed of'). Note that in the minimum table 

set, a special relationship label, "Attributed by," is reserved to relate Attribute Value records to their owner(s) 

(objects, attribute values, or relationships)--it is not used when an Attribute Assignment table is pres~t. 

(b) Reverse Relationship Label - Name given to the reverse relationship (e.g., "Part of'). Note that if the relationship is symmetrical (the order of the elements of the tuple is not significant), this name would be the same as 

the forward Relationship Label. 

(c) Relationship Authority - Source of the definition for this relationship (e.g., "USGS/NMD, DLG-E"). 

(d) Domain of the First Tuple Element - indicates what type of objects may participate as the first eletr<mt in the 

Relationship Tuple table. One of the single character "object" type codes listed above is carried in this field. 

In the minimum table set, this be may be F, V, or R. However, when an Attribute Assignment tab ~ is present, 

only feature objects may be first tuple elements; this field will always carry "F." It is therefore unn~.cessary, but 

we keep it for compatibility with the minimum table set and for future expansion. 

(e) Domain of the Second Tuple Element - indicates what type of objects may participate as the seconCl element in 

the Relationship Tuple table. In the minimum table set, the following single character "object" type codes may 

be present in this field: P, N, C, A, F, V, or R. When an Attribute Assignment table is present, only true 

object codes (P, N, C, A, and F) may be present. 

(f) Ordered? - must be Y (yes), N (no) or E (either). 

(g) Directed? - this field is important only with Ordered relationships; if Y (yes), then the order of secC'-qd tuple 

elements indicates a "ground" direction important to the composition of the real-world entity represe"'.ted by the 

first tuple element (e.g., a Stream has a direction of flow). 

(h) Flag Field Meaning - this defmes the meaning of the contents of the flag field in the Relationship t··ple records 

(e.g., a negative sign in the field indicates the coordinate string of the referenced chain is to be reversed for this 

relationship). 

=============================================== 

1. Name of Table: Attribute Value 

2. Pwpose: This table serves to store the actual attribute values of attributes associated with (1) feature ob}~.cts, (2) 

other attribute values, or (3) relationships. 

3. Key field name: Attribute Value Key 

Unique?: NO--a set of attribute values (one value per record) may be referenced as a whole (by one fo:"eign 

identifier) if needed and there is no need to reference each individual value of the set. 

To produce a unique key for the Attribute Value records, the Order Sequence Number field (5.(b) below) is concatenated to the Attribute Value Key field. 

Construction: "V" + 5 digits. 

4. Foreign ID field: 

Attribute Definition Key (to the Attribute Definition table). 

5. Other field: 

(a) Attribute Value -- the actual attribute value data item (as a set of bytes, which are to be interpreted per the 

Attribute Value Format field of the referenced Attribute Definition record). 

(b) Order Sequence Number - if the value is part of a set (and the records have the same Attribute Value Key), this 

field provides sequencing data (an integer from 1 to N, the number of values in the set). Also, this field 

concatenated with the Attribute Value Key field yields a unique key for an individual record. 

=============================================== 

8·26 An Enhanced Digital Line Graph Design 
1. Name of Table: Name/Text 

2. Purpose: This table serves to store the actual "long" alphanumeric attribute values of attributes associated with (1) 

feature objects, (2) other attribute values, or (3) relationships. Examples of these "long" attribute values are those 

assigned to the attributes labeled "Name" or "Comment" (in the Attribute Label field of the Attribute Definition 

table). 

3. Key field name: Name{fext Key 

Unique?: NO--a set of alphanumeric strings (one string per record) may be referenced as a whole (by one foreign 

identifier) if needed and there is no need to reference each individual string of the set. In this manner, for example., 

a single attribute may be valued by a very long text passage entered as a set of text lines, one line per Feature 

Name{fext record, and the entire record set would be identified by a single key shared by all the records of the set. 

To produce a unique key for the Name{fext records, the Order Sequence Number field (5(b) below) is concatenated 

to the Name{fext Key field. 

Construction: ''T" + 5 digits. 

4. Foreign ID field: 

Attribute Definition Key (to the Attribute Definition table). 

5. Other fields: 

(a) Name{fext String -- the actual alphanumeric text string comprising the value of the referenced Attribute (e.g., 

Name). 

(b) Order Sequence Number - if the string is part of a set, this field provides sequencing data (an integer from 1 t, 

N, the number of strings in the set). Also, this field concatenated with the Name{fext Key field yields a uniqrJe 

key for an individual record. 

=============================================== 

1. Name of Table: Attribute Assignment 

2. Purpose: This table provides the means by which (1) attribute values, and (2) names/text, are assigned to 

(a) feature objects, (b) relationships (as instanced in the Relationship Tuple records), (c) attribute assignments (as 

instanced in the records of this table), (d) other attribute values, and (e) other feature names/text This table also 

provides the means by which entity labels are assigned to only feature objects. 

3. Key field name: Attribute Assignment Key 

Unique?: NO--a set of tuples (one pair per record) may be referenced as a whole (by one foreign identifier) if 

needed and there is no need to reference each individual record of the set. 

To produce a unique key for the Attribute Assignment records, the Order Sequence Number field (5 below) is 

concatenated to the Attribute Assignment Key field. 

Construction: "S" + 5 digits. 

4. Foreign ID field(s): 

(a) Element ID - the Feature Object, Relationship Tuple, Attribute Assignment, Attribute Value, or Feature 

Name/fext record key of the element to which the attribute is assigned. 

(b) Attribute ID - the Attribute Value, Name{fext, or Entity Label record key of the value(s), name/text, or entity 

label assigned to the element identified by the Element ID. 

5. Other field: 

Order Sequence Number - if an Attribute Assignment record is part of a set (with a common Attribute 

Assignment Key), this field provides sequencing data (an integer from 1 to N, the number of records in t1e 

set). Also, this field concatenated with the Attribute Assignment Key field yields a unique key for an 

individual record. 

=============================================== 

Appendix B ~~7 
1. Name of Table: Relationship Tuple 

2. Purpose: This is an object linkage table. Feature and topological objects are related to feature objects t1rough 

named relationships (defined in the Relationship Definition table). 

3. Key field name: Relationship Tuple Key 

Unique?: NO--a set of tuple records may and should be referenced as a whole (by one foreign identifie:"') if the set 

of Second Tuple Elements instance a one-to-many relationship to the feature object identified in the First. Tuple 

Element. 

To produce a unique key for the Relationship Tuple records, the Order Sequence Number field (5(b) bek>w) is 

concatenated to the Relationship Tuple Key field. 

Construction: "R" + 5 digits. 

4. Foreign ID field(s): 

(a) Relationship Definition Key - to the Relationship Defmition Table. 

(b) First Tuple Element - the feature object ID of the first element in this relationship tuple. 

(c) Second Tuple Element - the object (feature or topological) ID of the second element of this relationship tuple. 

5. Other fields: 

(a) Flag - this field may be used to attach a simple qualifier to this relationship. For example, a sign may be 

included in this field to indicate the direction of a chain coordinate string included in a linear feanre. 

(b) Order Sequence Number - if a set of Second Tuple Elements (in records with identical Relationship Tuple Keys) 

instance a one-to-many relationship to the feature object identified in the First Tuple Element and tl'~ relationship is an ordered one, this field provides sequencing data (an integer from 1 to N, number of reco·<ts in the 

set), and when concatenated with the Relationship Tuple Key field yields a unique key for an indiv!rJual record. 

Table/Field Summary 

The following summarizes the record layout of each table, including a FORTRAN record format and an item~-r.ed field 

list. For each field, a short mnemonic is given as well as the full field name and fixed field byte positions within the 

record. 

Feature Object Table: 

((A1,15),1X,(A1,15),1X,Il,1X,Al,1X,A1,1X,I2,1X,I3,1X,Il,1X,I2,1X,I2) 

Mnemonic 

FKEY 

PEID 

DIMN 

COMP 

CNTG 

NREL 

NRTR 

NELB 

NAYS 

NNTS 

1- 6 

8-13 

15 

17 

19 

21-22 

24-26 

28 

30-31 

34-34 

Entity Label Table: 

((A1,l5),1X,A22,1X,A8) 

Mnemonic 

EKEY 

ELABL 

EAUTH 

1- 6 

8-29 

31-38 

Full Field N arne 

Feature Object Key 

Primary Entity Label Foreign ID 

Dimensionality 

Composition 

Contiguous? 

Number of Relationships 

Number of Relationship Tuple Records 

Number of Entity Labels Assigned 

Number of Attribute Value( Set)s Assigned 

Number of Name{fext String( Set)s Assigned 

Full Field N arne 

Entity Label Key 

Entity Label 

Definition Authority 

8·28 An Enhanced Digital Line Graph Design 
Attribute Definition Table: 

((A2,14),1X,A36,1X,A8,1X,Al,lX,A8) 

Mnemonic Cols. 

AD KEY 1- 6 

ALABL 8-43 

AAUTH 45-52 

AVFMT 54 

UNITS 56-63 

Full Field N arne 

Attribute Definition Key 

Attribute Label 

Attribute Definition Authority 

Attribute Value Format 

Attribute Value Measurement Units 

Relationship Definition Table: 

((A2,14),2X,A22,1X,A24,1X,A5,1X,A1,1X,Al,1X,A1,1X,A1,1X,A56) 

Mnemonic Cols. 

RDKEY 1- 6 

RLABL 9-30 

REVLB 32-55 

RAUTH 57-61 

DOMNl 63 

DOMN2 65 

ORD 67 

DIR 69 

MNG 71-126 

Attribute Value Table: 

((A1,15),1X,(A2,14),1X,A18,1X,I3) 

Mnemonic Cols. 

VKEY 1- 6 

ADID 8-13 

AVAL 15-32 

SEQN 34-36 

Nameffext Table: 

((A1,15),1X,(A2,14),1X,A60,1X,I3) 

Mnemonic Cols. 

TKEY 1- 6 

ADID 8-13 

TEXT 15-74 

SEQN 75-77 

Attribute Assignment Table: 

((Al,I5),1X,(Al,l5),1X,(Al,I5),1X,l3) 

Mnemonic Cols. 

SKEY 1- 6 

EFID 8-13 

AFID 15-20 

SEQN 22-24 

Full Field Name 

Relationship Defmition Key 

Relationship Label 

Reverse Relationship Label 

Relationship Defmition Authority 

Domain, First Tuple Element 

Domain, Second Tuple Element 

Ordered? 

Directed? 

Flag Meaning 

Full Field Name 

Attribute Value Key 

Attribute Definition Foreign ID 

Attribute Value (Note: actual format of this field is in the A VFMT field in the 

Attribute Definition table.) 

Order Sequence Number 

Full Field N arne 

Name{fext Key 

Attribute Defmition Foreign ID 

Name{fext String 

Order Sequence Number 

Full Field Name 

Attribute Assignment Key 

Element (object types F, E, V, T, R, S) Foreign ID 

Attribute ("object" types E, V, T) Foreign ID 

Order Sequence Number 

Appendix 8·29 
Relationship Tuple Table: 

((A 1 ,15), 1X,(A2,14 ), 1X,(A1 ,15), 1X,(A1 ,15), 1X,A 1, 1X,I3) 

Mnemonic 

RKEY 

ROID 

EliD 

E2ID 

FLAG 

SEQN 

Cols. 

1- 6 

8-13 

15-20 

22-27 

29 

31-33 

Full Field Name 

Relationship Tuple Key 

Relationship Definition Foreign ID 

First Tuple Element (object type F) Foreign 10 

Second Tuple Element (types F, P, N, A, C) Foreign 10 

Flag 

Order Sequence Number 

Foreign IO's Pointing to "Object" Keys 

The following diagrams are meant to show how the contents of foreign identifier fields in the OLG-0+ table records 

point to the key fields of other records. The Feature Object table is a special case in that many of its fields (with the 

exception of Primary Entity ID field--PEID) do not necessarily point other records, but they do provide counts and other 

summary information about the records in other tables (namely the Attribute Assignment and Relationship Tuple ta'>les). 

An attempt has been made to illustrate cross-references between fields of the different tables by listing the fields o~ a 

given table frrst, followed by a listing of the fields of each of the tables to which the records of the first table may point. 

Exact field-to-field references are shown by using different highlighting techniques (i.e. bold, italics, underline, and 

shadow). 

Feature Object Table: 

lPKEY PEID DIMN COMP CNI'G NREL NRTR NELB NA VS NNTS 

Entity Label Table: 

EKEY ELABL EAUTH 

Relationship Tuple Table: 

RKEY ROID lBtm E210 FLAG SEQN 

Attribute Assignment Table: 

SKEY lB1Fm AFID SEQN 

PEID (Feature Object table) points to EKEY (Entity Label table). 

DIMN COMP CNI'G NREL NRTR summarize information in those Relationship Tuple Table records where 

lBlJIII) = JPKEY. 

NELB NA VS NNTS count the number of unique SKEY values in those Attribute Assignment Table records 

where IBlFliD = lFKIBY. 

Relationship Tuple Table: 

RKEY RDID EliD E21D FLAG SEQN 

Relationship Defmition Table: 

RDKEY RLABL REVLB RAUTH DOMNl DOMN2 

Feature Object Table: 

FKEY PEID DIMN COMP CNTG 

Node, Area, and Line Id Records in DLG-0 file: 

(Record Type. Element ID number) ... 

RDID points to RDKEY (Relationship Definition table). 

EliD points to FKEY (Feature Object table). 

B-30 An Enhanced Digital Line Graph Design 
E2ID may point to FKEY (Feature Object table), or to Record Tvpe + Element ID number in a DLG-0 Node, Line, 

or Area ld Record. 

Attribute Assignment Table: 

SKEY EFID AFID SEQN 

Feature Object Table: 

FKEY PEID DIMN COMP CNTG 

Relationship Tuple Table: 

RKEY RDID EliD E2ID FLAG SEQN 

Attribute Assignment Table (other records): 

SKEY EFID AFID SEQN 

Attribute Value Table: 

VKEY ADID A VAL SEQN 

Name{fext Table: 

TKEY ADID TEXT SEQN 

Entity Label Table: 

EKEY ELABL EAUTH 

EFID may point to any of the key fields (i.e. FKEY, RKEY, SKEY, VKEY, TKEY, or EKEY) of the six tables 

listed. 

AFID may point to VKEY, TKEY, or EKEY. 

Attribute Value Table: 

VKEY ADID AVAL SEQN 

Attribute Definition Table: 

ADKEY ALABL AAUTH AVFMT UNITS 

ADJD points to ADKEY (Attribute Definition table). 

Name{fext Table: 

TKEY ADID TEXT SEQN 

Attribute Definition Table: 

ADKEY ALABL AAUTH AVFMT UNITS 

ADlD points to ADKEY (Attribute Definition table). 

Appendix B-31 
7. CASE EXAMPLES 

Several examples illustrate how the source, product specification, and representation rules work together to rroduce digital 

representations of features in the DLG-0+ data set. The examples lead the reader through many of the relrtional tables, 

showing how information is stored and linked. 

This section presents a number of individual cases illustrating how DLG-E features are represented in the I:,.. ..0-E 

example data set. Feature instances, summarized in section 4, have been extracted from the source material:~ in section 2 

based upon the feature and attribute definitions in appendix A and the DLG-E feature data specifications in section 3. 

The representations of these feature instances, also based on rules in section 3, have been implemented usinn the 

DLG-0+ relational tables defined in section 6, and an associated DLG-0 file as plotted in section 5. As c.,.n be seen, 

all parts of this appendix are required to follow the examples in this section. 

In pursuing a given example, the reader is encouraged to gather in front of him or her the source graphic (page B-3), the 

graph plots (pages B-20 and B-21), and the five full DLG-0+ relational tables below (pages B-33 through B-37). The 

Table/Field Summary (pages B-28 through B-30) can serve as reference for the full field names of the table<;'. 

Each of the examples presents one primary feature instance from the source graphic and follows its represerr.ation through 

the DLG-0+ relational tables and the DLG-0 chain and area plots. In the process, related feature instance~ .. where 

found, are also discussed. In this manner, instances of both the Road and Underpass features are included in the first 

example; instances of the Stream/River, Shoreline, and Junction features are presented in the second example; and 

instances of the Reservation and Boundary Line features are covered in the third example. 

As discussed in section 6, the DLG-0+ relational tables make extensive use of "object" keys and foreign llYs. Each of 

the table records has its object key by which it can be referenced by foreign ID's in other table records (se~ pages B-30 

to B-31). When discussing the case examples, the primary focus is on feature instances. As such, the path through the 

relational tables begins with a record in the Feature Object table, and following the foreign ID pointers, pro~eeds as 

follows: 

1. The Feature Object record contains the key value ("F" + ID number) for the instance and points to it1~ Entity Label 

(i.e. feature term) in the Entity Label table (as well as summarizes related records in the Attribute As~i.gnment and 

Relationship Tuple tables); 

2. The Attribute Assignment table assigns Attribute Value and Name/Text records to the feature object (and to other 

"objects" (e.g., other attribute values) as well); 

3. The Attribute Value and Name/Text records contain actual values and text strings; each of these records points to 

its Attribute Label (i.e. attribute term) and associated value format in a record of the Attribute Definition table. 

4. The Relationship Tuple records relate objects in the DLG-0 file (points, nodes, chains, and areas), as well as other 

feature objects, if appropriate, to feature objects. Each Tuple record also points to a Relationship Definition table 

record which defines which relationship is being instanced. 

FULL DLG-E EXAMPLE DATA SET TABLES 

Five of the eight DLG-0+ relational tables defined for DLG-E data are relatively brief for the DLG-E example data set. 

The Entity Label, Attribute Definition, Relationship Definition, Attribute Value, and Name/Text tables are irr:luded here in 

their entirety for use by each of the examples to follow. For the Feature Object, Attribute Assignment, anc Relationship 

Tuple tables, those records (and only those records) pertaining to the actual case examples will be presented within the 

context of the discussion of the example. Note: the column headings in each of the example tables are th~ field 

mnemonics presented in the Table/Field Summary in section 6 (pages B-28 to B-30). 

8·32 An Enhanced Digital Line Graph Design 
Entity Label Table (in its entirety): 

EKEY 

EOOOOl 

E00002 

E00003 

E00004 

EOOOOS 

E00006 

E00007 

EOOOOS 

E00009 

EOOOlO 

EOOOll 

E00012 

E00013 

E00014 

E00015 

E00016 

E00017 

E00018 

E00019 

E00020 

E00021 

E00022 

E00023 

E00024 

~ 

NAMED FEATURE 

ROAD 

RAILWAY 

STREAM 

LAKE 

SPRING 

DAM 

SHORELJNE 

JUNCfiON 

NATION 

STATE/fERRITORY 

COUNTY 

DOMAIN 

PUBUC SURVEY DOMAIN 

RIDGE 

CEMETERY 

INSTITUTIONAL SITE 

RESERVATION 

BRIDGE 

BUILDING 

UNDERPASS 

TRAIL 

FORD 

BOUNDARY LINE 

EAUTH 

USGS!NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGSINMD 

USGS!NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

This table is a list of the 24 DLG-E features (types, not instances) found in the contrived source materials. Each feat .. Te 

instance is represented by a feature object. Each Feature Object record contains a pointer to one record in the Entity 

Label table, indicating which type of feature is being instanced. The Attribute Assignment table also contains records 

which relate Entity Labels to Feature Objects (as such these records are redundant when only one Entity Label is assirned 

to a given Feature Object). 

Appendix B-33 
Attribute Definition Table (in its entirety): 

AD KEY 

ADOOOl 

AD0002 

AD0003 

AD0004 

ADOOOS 

AD0006 

AD0007 

AD0008 

AD0009 

ADOOlO 

ADOOll 

AD0012 

AD0013 

AD0014 

AD0015 

AD0016 

AD0017 

AD0019 

AD0020 

AD0021 

AD0022 

AD0023 

AD0024 

AD0025 

AD0026 

AD0027 

AD0029 

AD0030 

ALABL 

ACCESS RESTRICTION 

NAME 

ROUTE DESIGNATOR 

OPERATIONAL STATUS 

ROAD CLASS 

TRAFFIC DIRECTION 

NUMBER OF LANES OR TRACKS 

RAILWAY GAUGE 

HYDROGRAPIDC CATEGORY 

WATER CHARACTERISTIC 

MATERIAL COMPOSITION 

SPILLWAY ELEVATION 

DELINEATION STATUS 

FIPS CODE IDENTIFIER FIRST 

PIPS CODE IDENTIFIER SECOND 

ORIGIN OF SURVEY NAME 

RANGE 

TOWNSHIP 

INSTITUTIONAL FUNCTION 

RESERVATION TYPE 

RESERVATION USE STATUS 

COVERING 

NUMBER OF DECKS 

ANGLE OF ORIENTATION 

BUILDING CLASS 

TRAIL TYPE 

ROUTE TYPE 

COMMENT 

AAUTH 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

USGS/NMD 

AVFMT UNITS 

A 

A 

A 

A 

A 

A 

I 

A 

A 

A 

A 

I FEET 

A 

A 

A 

A 

A 

A 

A 

A 

A 

A 

I 

I DEGREES 

A 

A 

A 

A 

This table contains a record for each unique Attribute Label term used in the DLG-E example data set. Eac"l Attribute 

Value and Name/Text record contains a pointer to a record in this table, indicating which Attribute is being valued. 

Also, the A VFMT field in this table indicates how to read the A VAL field in the Attribute Value record, and for numeric 

attribute values, the UNITS field indicates the units of measure. 

8·34 An Enhanced Digital Line Graph Design 
RelationshiE Definition Table (in its entirety): 

RDKEY RLABL REVLB RAUTH 

RDOOOl Composed of Part of DLG-E 

RD0002 Composed of Part of DLG-E 

RD0003 Composed of Part of DLG-E 

RD0004 Composed of Part of DLG-E 

RD0005 Composed of Part of DLG-E 

RD0006 Composed of Part of DLG-E 

RD0007 Composed of Part of DLG-E 

RD0008 Composed of Part of DLG-E 

RD0009 Composed of Part of DLG-E 

RDOOlO Bounded by Bounds DLG-E 

RDOOll Vert. relates Vert. related by DLG-E 

RD0013 Flows to Flows from DLG-E 

RD0014 Connects to Connects to DLG-E 

DOMN1 DOMN2 ORD 

F p N 

F N N 

F c N 

F A N 

F F N 

F c y 

F F y 

F c y 

F F y 

F F E 

F F y 

F F N 

F F E 

DIR 

N 

N 

N 

N 

N 

N 

N 

y 

y 

y 

N 

y 

y 

F1 

Fl 

Fl 

F2 

01 

Each Relationship Tuple record contains a pointer to a record in this table indicating what relationship is being instane<-.d. 

The relationships are those listed as "nontopological" in table 4 in "Concepts of DLG-E Design," page 5, with added 

distinctions made to the "composed of/part of'' relationship (by object types, ordering of members of a relationship tupl ~ 

set, and "ground" significance of direction). 

Note that the Flag Meaning field (MNG) has been shortened to allow listing here. The following explains how the Flag 

Meaning field (MNG) indicates the meaning of the Relationship Tuple record FLAG and/or SEQN field contents: 

Fl 

"+" 

F2 

"+" 

01 

"1" 

"2" 

Flag Meaning # 1 

in the FLAG field of the Relationship Tuple record indicates that the direction defmed by the order of 

the coordinates of the one-dimensional object referenced by E2ID (chain for RD0006 and RD0008, and 

feature for RD0009) matches the direction of the feature object referenced by E1ID. 

in the FLAG field indicates that the direction defined by the order of the coordinates of the onedimensional object referenced by E2ID is the opposite of the direction of the feature object referenced 

by E1ID. 

Flag Meaning #2 

in the FLAG field of the Relationship Tuple record indicates that the direction of the one-dimensio:rsd 

feature object referenced by E2ID is clockwise around the bounded two-dimensional feature object 

referenced by EliD (area is to the right). 

in the FLAG field indicates that the direction of the one-dimensional feature object referenced by E2ID 

must be reversed to allow the bounded object referenced by E1ID to be to the right. 

Order Meaning #1 

in the SEQN field of the Relationship Tuple record indicates that the feature object referenced by 

E2ID is the "above" feature. 

in the SEQN field indicates that the E2ID feature is "below." 

Appendix 8-35 
Attribute Value Table (in its entirety): 

VKEY ADID AVAL [SEQN is not used] 

VOOOOl ADOOOl NONE 

V00004 AD0004 OPERATIONAL 

V00005 AD0005 1ST 

V00006 AD0006 TWO WAY 

V00007 AD0007 2 

V00014 AD0007 4 

V00031 AD0003 US63 

V00041 AD0006 ONE WAY 

V00052 AD0003 I-44 

V00061 AD0005 2ND 

V00087 AD0003 ROUTE CC 

V00115 AD0003 ROUTE 2 

V00121 AD0027 UNKNOWN 

V00124 AD0007 1 

V00126 AD0008 STANDARD 

V00129 AD0003 #UNSPECIFIED 

V00131 AD0005 3RD 

V00141 AD0009 PERENNIAL 

V00147 AD0009 INTERMITTENT 

V00162 ADOOlO UNSPECIFIED 

V00163 ADOOll EARTHEN 

V00165 AD0012 974 

V00166 AD0013 DEFINITE 

V00167 ADOOlO FRESH 

V00174 AD0014 34 

V00176 AD0015 101 

V00178 AD0015 102 

V00179 AD0016 USGLO 

V00180 AD0017 39E 

V00182 AD0019 6S 

V00184 AD0017 40E 

V00189 AD0020 EDUCATION 

V00190 AD0022 STATE 

V00192 AD0023 NOT COVERED 

V00194 AD0024 1 

V00195 AD0026 1 

V00196 AD0025 0 

V00204 AD0013 INDEFINITE 

V00231 AD0021 PARK 

V00240 AD0029 ALTERNATE 

V00241 AD0029 UNSPECIFIED 

This table contains a record for each unique attribute value assigned (by the Attribute Assignment table) to ore or more 

feature objects or to other attribute values. The ADID field points to an Attribute Definition record indicatinr how to 

read the value. 

B-36 An Enhanced Digital Une Graph Design 
Name/fext Table (in its entirety): 

TKEY 

TOOOOl 

T00002 

T00003 

T00004 

TOOOlO 

TOOOll 

T00012 

T00014 

T00015 

T00016 

T00017 

TOOl 52 

TOOl 58 

T00160 

T00173 

T00175 

T00177 

T00187 

T00188 

T00244 

ADID 

AD0002 

AD0002 

ADOQ02 

AD0002 

AD0002 

AD0002 

AD0002 

AD0030 

AD0030 

AD0030 

AD0030 

AD0002 

AD0002 

AD0002 

AD0002 

AD0002 

AD0002 

AD0002 

AD0002 

AD0002 

TEXT 

BISHOP AVENUE 

#UNKNOWN 

UNITED STATES OF AMERICA 

SPOONER COLLEGE 

LANE SPRINGS STATE PARK 

EAST FORK LAKE 

MEMORIAL DRIVE 

From the County Engineer 

From local residents and businessmen 

From the Highway Department 

[ SEQN is not used ] 

From Park Admin Office: trail is part of the park. 

MIDDLE FORK 

EAST FORK 

MILL CREEK 

MISSOURI 

PHELPS 

DENT 

PEA RIDGE 

#UNSPECIFIED 

#NOT APPUCABLE 

This table contains a record (with ADID = "AD0002") for each unique name assigned (by the Attribute Assignment taHe) 

to a feature object. Special records with the contents of the TEXT field beginning with "#" are used to indicate the 

status of assigning a name, rather than a name itself (an actual name is not recorded). 

This table also contains comments (ADID = "AD0030") which may be assigned to any nontopological "object." In the 

DLG-E example data set, three such records indicate the source of an attribute value assignment, and a fourth comments 

a relationship tuple record. 

Appendix 8·37 
ROAD AND UNDERPASS EXAMPLE 

U.S. 63 is a feature instance running north-south through the source graphic. The contrived field notes indicate that the 

route is actually Alternate U.S. 63. This instance is obviously a road, but along its length, some of its attribrt.e values 

(e.g., number of lanes) change. Each of the coherent parts of Alternate U.S. 63 with consistent attribute valu~s is 

therefore recorded as an individual road feature instance. There are four such road instances, with object !D's F00001 

through F00004. Feature object F00005, composed of F00001 through F00004 (the Relationship Tuple set wi+lt RKEY = 

"R00005" tells us this), represents the entire length of Alternate U.S. 63. Since the representation rules for "Poad" 

(EKEY = "E00002") dictate that a road instance can only be composed of chains or areas, however, F00005 is classified 

as a "Named Feature" (EKEY = "E00001 ") instance instead. 

The first road feature object (FOOOOl) of Alternate U.S. 63 is also related to other feature objects through Rel .. tionship 

Tuple records (with RKEYs = "R00064" and "R00065" directly to F00057, F00058, F00006, and F00007, and with 

RKEY = "R00008" indirectly to F00008). All Feature Object records related to this example then are as foll<'ws: 

Feature Object Table (road and underpass example): 

FKEY PEID DIMN COMP CNTG NREL NRTR NELB NAVS NNTS 

F00001 E00002 1 c y 1 4 1 6 1 

F00002 E00002 1 c y 1 1 1 6 1 

F00003 E00002 1 c y 1 1 1 6 1 

F00004 E00002 1 c y 1 1 1 6 1 

F00005 E00001 1 F y 1 4 1 0 1 

F00006 E00002 1 c y 1 7 1 5 1 

F00007 E00002 1 c y 1 7 1 5 1 

F00008 E00001 1 F N 1 2 1 3 0 

F00057 E00021 0 N y 2 3 1 0 0 

F00058 E00021 0 N y 2 3 1 0 0 

F00005 and F00008 are both one-dimensional "Named Features" consisting of individual "Road" feature object~ F00005 

is contiguous and is composed of an ordered set (but with no ground significance to the order). Its one-dimersional road 

feature objects (F00001 through F00004) consist of ordered sets of chains (also with no ground significance to the order). 

F00008 on the other hand, representing 1-44, is composed of a noncontiguous, unordered set consisting of F00006 (eastbound lanes) and F00007 (west-bound lanes). Each of these objects consists of an ordered set of chains, with ground 

significance (traffic travels in the direction specified by the order of the coordinates of the chains, as modified by the 

FLAG field). F00057 and F00058 are zero-dimensional "Underpass" features (EKEY = "E00021 ") each compc~ed of a 

node. F00001 is vertically related to (placed above) F00006 and F00007 at these underpass features (U.S. 63 passes over 

1-44). The Relationship Tuple records related to this example then are: 

Relationship Tuple Table (Road and Underpass Example): 

RKEY 

R00001 

R00001 

R00001 

R00001 

R00002 

R00003 

R00004 

R00005 

R00005 

R00005 

R00005 

R00006 

R00006 

R00006 

R00006 

R00006 

R00006 

R00006 

R00007 

8·38 

RDID EliD E2ID 

RD0006 F00001 C00007 

RD0006 F00001 COOOll 

RD0006 F00001 C00040 

RD0006 F00001 C00047 

RD0006 F00002 C00062 

RD0006 F00003 C00073 

RD0006 F00004 C00077 

RD0007 F00005 F00001 

RD0007 F00005 F00002 

RD0007 F00005 F00003 

RD0007 F00005 F00004 

RD0008 F00006 C00012 

RD0008 F00006 C00018 

RD0008 F00006 C00020 

RD0008 F00006 C00026 

RD0008 F00006 C00029 

RD0008 F00006 C00031 

RD0008 F00006 C00032 

RD0008 F00007 C00027 

An Enhanced Digital Line Graph Design 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

SEQN 

1 

2 

3 

4 

1 

1 

1 

1 

2 

3 

4 

1 

2 

3 

4 

5 

6 

7 

1 
RKEY RDID EliD E2ID FLAG SEQN 

R00007 RD0008 F00007 C00024 + 2 

R00007 RD0008 F00007 C00016 + 4 

R00007 RD0008 F00007 C00022 + 3 

R00007 RD0008 F00007 C00014 5 

R00007 RD0008 F00007 COOOlO + 6 

R00007 RD0008 F00007 C00008 + 7 

R00008 RD0005 F00008 F00006 1 

R00008 RD0005 F00008 F00007 2 

R00060 RD0002 F00057 N00012 

R00061 RD0002 F00058 N00016 

R00064 RDOOll F00057 FOOOOl 1 

R00064 RDOOll F00057 F00007 2 

R00065 RDOOll F00058 FOOOOl 1 

R00065 RDOOll F00058 F00006 2 

Specifically, to trace the attribution of Alternate U.S. 63 (F00005): 

1. SOOOlO assigns TOOOOl, the name ''Bishop Avenue" 

2. Names (AD0002) and "Number of Lanes" (AD0007) change over the length of Alternate U.S. 63, so these attributes 

are valued at the road feature instance level represented by objects FOOOOl through F00004. 

a) V00007, valuing ''Number of Lanes" at 2, is assigned to FOOOOl, F00003, and F00004 (by S00008, S00025, and 

S00033 respectively). 

b) V00014, valuing "Number of Lanes" at 4, is assigned to F00002 by S00017. 

c) F00002 is named "Memorial Drive" (SOOOll assigning T00012). S00271 identifies the source for naming 

F00002 "Memorial Drive" by assigning a comment (T00015--"From local residents and businessmen") to 

SOOOll. 

3. The following attribute values are assigned to the road feature instances (objects FOOOOl through F00004): 

a) VOOOOl, which values "Access Restriction" (ADOOOl) as "None." 

b) V00004, which values "Operational Status" (AD0004) as "Operational." 

c) VOOOOS, which values "Road Class" as "1st." 

d) V00006, which values "Traffic Direction" as "Two way." 

e) V00031, which values "Route Designator" as "US63." 

4. S00261 further attributes V00031 ("US63") by assigning V00240, which values "Route Type" (AD0029) as "Alternate." 

5. S00273 further comments on the source of "Alternate" by assigning T00016 ("From the Highway Department") tC' 

S00261. 

The Attribute Assignment records listed below also include records for feature objects representing 1-44 (F00006, F00007, 

and F00008) and for the two Underpass features (no attribute values are assigned, just the E00021 entity label). The 

Attribute Assignment records related to this example then are as follows: 

Attribute Assignment Table (Road and Underpass Example): 

[Note: to save space, the records are listed here in two colunms; there are only three fields per record (SEQN is not 

used).] 

SKEY EFID AFID SKEY EFID AFID 

SOOOOl FOOOOl E00002 S00026 F00004 E00002 

S00002 FOOOOl VOOOOl S00028 F00004 T00002 

S00003 FOOOOl T00002 S00033 F00004 V00007 

soooos FOOOOl V00004 S00034 FOOOOS EOOOOl 

S00006 FOOOOl V00005 S00035 FOOOOl V00031 

S00007 FOOOOl V00006 S00036 F00006 E00002 

S00008 FOOOOl V00007 S00037 F00006 VOOOOl 

S00009 F00002 E00002 S00038 F00006 T00002 

SOOOlO F00005 TOOOOl S00040 F00006 V00004 

SOOOll F00002 T00012 S00041 F00006 voooos 

S00017 F00002 V00014 S00042 F00006 V00041 

S00018 F00003 E00002 S00043 F00006 V00007 

S00020 F00003 T00002 S00044 F00007 E00002 

S00025 F00003 V00007 S00046 F00007 T00002 

Appendix B-39 
SKEY EFID AFID SKEY EFID AFID 

S00050 F00007 V00041 S00281 F00002 V00006 

S00051 F00007 V00007 S00282 F00002 V00031 

S00052 F00008 E00001 S00283 F00003 V00001 

S00053 F00008 V00052 S00284 F00003 V00004 

S00248 F00057 E00021 S00285 F00003 V00005 

S00249 F00058 E00021 S00286 F00003 V00006 

S00261 V00031 V00240 S00287 F00003 V00031 

S00262 V00052 V00241 S00288 F00004 V00001 

S00271 SOOOll T00015 S00289 F00004 V00004 

S00272 S00261 T00016 S00290 F00004 V00005 

S00274 F00008 V00006 S00291 F00004 V00006 

S00275 F00008 V00014 S00292 F00004 V00031 

S00278 F00002 V00001 S00293 F00007 V00001 

S00279 F00002 V00004 S00294 F00007 V00004 

S00280 F00002 V00005 S00295 F00007 voooos 

STREAM/RIVER, SHOREL1NE, AND JUNCTION EXAMPLE 

Mill Creek is a "Stream/River" (EKEY = "E00004") feature instance discernible on the source graphic, beginning north of 

I-44 at the discharge of an intermittent pond. It proceeds as an intermittent stream until a point near Pea Ridg~, As Mill 

Creek continues southward, it becomes wide enough to be displayed as an areal feature (a water body bounded by a 

"Shoreline" (EKEY = "E00008")). This water body flows "out" of the map area at the south neatline. The indication of 

the direction of stream flow is carried by the modified (by the FLAG field) order of coordinates of the chains comprising 

the stream/river feature objects. When a stream is represented by an area, however, a "Junction" (EKEY = "E00009") 

feature object is often required to participate with the areal stream object in a "Flows to/flows from" relationship. 

The following Feature Object records relate to this Mill Creek example: 

Feature Object Table: 

FKEY PEID DIMN COMP CNTG NREL NRTR NELB NAVS NNTS 

F00022 E00004 2 A y 3 4 1 1 0 

F00023 E00004 1 c y 1 2 1 1 0 

F00024 E00004 1 c y 1 1 1 1 0 

F00025 E00004 1 c y 1 1 1 1 0 

F00026 E00004 1 c y 1 4 1 1 0 

F00032 E00001 M F y 1 5 1 0 1 

F00036 E00009 1 c y 1 1 1 0 0 

F00037 E00008 1 c y 1 4 1 1 0 

Feature Object F00032, classified as a "Named Feature" (EKEY = "E00001 "), represents all of Mill Creek withi, the 

source map. It is composed of five stream/river feature objects differentiated from one another based upon (a) composition (chains vs. areas), (b) attribute values (perennial vs. intermittent), and (c) junctions with other stream/river nbjects. 

F00022 represents the areal part of Mill Creek; F00023, the linear part downstream from the junction with East Fork; 

F00024, the perennial part upstream from East Fork; F00025, the intermittent part downstream from Middle For~-:: and 

F00026 represents Mill Creek upstream from Middle Fork. 

Feature Object F00022, the areal part of Mill Creek, is composed of two DLG-0 areas. It is bounded, to the right, by 

(relationship RDOOlO) feature object F00037, representing a shoreline feature instance composed of ordered chains. 

F00022 also flows into (relationship RD0013) object F00036, representing a junction feature instance. 

Objects F00023, F00024, F00025, and F00026 are each composed of an ordered set of chains (actually F00024 and 

F00025 consist of only one chain each). The order of the coordinates of these chains, as modified by the FLAG field 

("+" or "-"), represents the direction of stream flow. 

B-40 An Enhanced Digital Line Graph Design 
The Relationship Tuple records related to this example are as follows: 

Relationship Tuple Table (Stream/River, etc., example): 

RKEY RDID EliD E2ID FLAG SEQN 

900022 RD0004 F00022 A00037 1 

R00022 RD0004 F00022 A00038 2 

R00023 RD0008 F00023 C00093 1 

R00023 RD0008 F00023 C00065 + 2 

R00024 RD0008 F00024 C00057 + 

R00025 RD0008 F00025 C00043 

R00026 RD0008 F00026 C00038 + 1 

R00026 RD0008 F00026 C00034 + 2 

R00026 RD0008 F00026 C00017 + 3 

R00026 RD0008 F00026 C00009 + 4 

R00032 RD0009 F00032 F00022 1 

R00032 RD0009 F00032 F00023 2 

R00032 RD0009 F00032 F00024 3 

R00032 RD0009 F00032 F00025 4 

R00032 RD0009 F00032 F00026 5 

R00037 RD0006 F00036 C00108 + 1 

R00038 RD0013 F00022 F00036 

R00039 RD0006 F00037 C00078 1 

R00039 RD0006 F00037 C00071 + 2 

R00039 RD0006 F00037 C00102 3 

R00039 RD0006 F00037 C00107 + 4 

R00040 RD0010 F00022 F00037 + 

The attribution of Mill Creek, by Attribute Assignment records, is as follows: 

1. F00032 is named "Mill Creek" by S00177 assigning T00160. 

2. Through S00140, S00144, and S00148, respectively, F00022, F00023, and F00024 are assigned V00141, which vrlues 

"Hydrographic category" (AD0009) as "Perennial." 

3. Through S00152 and S00156, F00025 and F00026 are assigned V00147, which values "Hydrographic category" 

(AD0009) as "Intermittent." 

4. F00037, representing the shoreline of F00022, is assigned (by S00189) V00166, which values "Delineation Status" 

(AD0013) as "Defmite." 

Attribute Assignment Table (Stream/River, etc., example, in two columns): 

SKEY EFID AFID SKEY EFID AFID 

S00139 F00022 E00004 S00152 F00025 V00147 

S00140 F00022 V00141 S00155 F00026 E00004 

S00143 F00023 E00004 S00156 F00026 V00147 

S00144 F00023 V00141 S00176 F00032 EOOOOl 

S00147 F00024 E00004 S00177 F00032 T00160 

S00148 F00024 V00141 S00187 F00036 E00009 

S00151 F00025 E00004 S00188 F00037 E00008 

S00189 F00037 V00166 

RESERVATION AND BOUNDARY LINE EXAMPLE 

Lane Spring State Park is a feature instance which illustrates some interesting cases. The park is composed of two 

separate areal parts (one area is in the middle of the map, and the second area, labeled "LS SP," is at the lower edg~~ of 

the map). These two areas are connected by a trail which is also part of the park (see the contrived field notes). The 

trail and the two areas are each represented by a "Reservation" (EKEY = "E00018") feature object. Lane Spring SU!te 

Park as a whole is represented by a "Named Feature" (EKEY = "EOOOOl ") object composed of the three reservation 

objects. The trail is also represented by a separate "Trail" (EKEY = "E00022") object. It is debatable as to whethe· or 

not the additional reservation object was needed for the trail, or if Lane Spring State Park could be composed of the two 

areal reservation objects and the trail object directly. 

Appendix 8·41 
As represented per DLG-E specifications (section 3), a reservation feature instance is bounded by a "Boundary Line" 

(EKEY = "E00024") feature. In this case, the boundary of Lane Spring State Park is not represented by a sin;·de feature 

object (either basic or higher level) because an attribute value changes, it is not contiguous, and there is no nai'le 

attribute. The park is thus bounded by three boundary line feature objects. 

The following eight feature object records are related to this example: 

Feature Object Table (Reservation and Boundary Line example): 

FKEY PEID DIMN COMP CNTG ~ NRTR NELB NAYS NNTS 

F00018 E00022 1 c y 1 1 1 2 1 

F00048 E00018 2 A y 2 12 1 2 0 

F00049 E00018 2 A y 2 2 1 2 0 

F00050 E00001 M F y 1 3 1 0 1 

F00061 E00024 1 c y 1 5 1 1 0 

F00066 E00024 1 c y 1 1 1 1 0 

F00075 E00018 1 c y 1 1 1 2 1 

F00076 E00024 1 c y 1 16 1 1 0 

Feature object F00050 represents Lane Spring State Park. It is composed of a contiguous set of three reservation feature 

objects (F00048, F00049, and F00075). F00048 and F00049 are each composed of a contiguous set of DLG areas (ten 

areas for F00048 and only one for F00049). F00075 is composed of one chain. That same chain (C00075) co"'Uprises 

feature object FOOO 18, representing a trail feature instance. F00048 is bounded by two boundary line objects (P00066 and 

F00076), differentiated by the attribute "Delineation Status" (AD0013). F00049 is bounded by object F00061. Each 

boundary line object (F00061, F00066, and F00076) is composed of a contiguous ordered set of chains. Note t"-at there 

is no ground significance to the composition order of the coordinates of the boundary objects (as defined by FlAG 

modified chain coordinate order), BUT when these objects participate in a "Bounded by/Bounds" (RDOOIO) relationship, 

the direction does have ground significance that indicates to which side of the boundary the bounded feature instance lies. 

The following Relationship Tuple records relate to this example: 

Relationship Tuple Table (Reservation and Boundary Line example): 

RKEY RDID BUD E2ID FLAG SEQN 

R00018 RD0008 F00018 C00075 + 

R00051 RD0004 F00048 A00026 1 

R00051 RD0004 F00048 A00024 2 

R00051 RD0004 F00048 A00017 3 

R00051 RD0004 F00048 A00020 4 

R00051 RD0004 F00048 A00031 5 

R00051 RD0004 F00048 A00032 6 

R00051 RD0004 F00048 A00023 7 

R00051 RD0004 F00048 A00025 8 

2R00051 RD0004 F00048 A00029 9 

R00051 RD0004 F00048 A00028 10 

R00052 RD0004 F00049 A00039 

R00053 RD0005 F00050 F00048 1 

R00053 RD0005 F00050 F00049 2 

R00053 RD0005 F00050 F00075 3 

R00068 RD0006 F00061 C00077 + 1 

R00068 RD0006 F00061 C00076 + 2 

R00068 RD0006 F00061 C00074 + 3 

R00068 RD0006 F00061 C00072 4 

R00068 RD0006 F00061 C00078 + 5 

R00073 RD0006 F00066 C00063 + 

R00081 RDOOIO F00048 F00066 + 1 

R00081 RDOOIO F00048 F00076 + 2 

R00082 RDOOIO F00049 F00061 + 

R00088 RD0003 F00075 C00075 

R00089 RD0006 F00076 C00041 + 1 

R00089 RD0006 F00076 C00039 2 

8-42 An Enhanced Digital Line Graph Design 
RKEY RDID EUD E2ID FLAG SEQN 

R00089 RD0006 F00076 C00033 + 3 

R00089 RD0006 F00076 C00026 + 4 

R00089 RD0006 F00076 C00029 5 

R00089 RD0006 F00076 C00036 + 6 

R00089 RD0006 F00076 C00044 + 7 

R00089 RD0006 F00076 C00049 8 

R00089 RD0006 F00076 C00055 9 

R00089 RD0006 F00076 C00060 10 

R00089 RD0006 F00076 C00068 11 

R00089 RD0006 F00076 C00091 12 

R00089 RD0006 F00076 C00090 13 

R00089 RD0006 F00076 C00089 14 

R00089 RD0006 F00076 C00066 15 

R00089 RD0006 F00076 C00064 16 

The attribution of F00050, the entire state park, is implemented as follows: 

1. S00227 assigns T00010 (Name text = "Lane Spring State Park"). 

2. S00273 assigns a comment (T00017, "From Park Admin. Office: trail is part of the park") to R00088, the Relat~()nship Tuple record which defines the composition of F00075, the trail part of F00050. 

The attribution of the basic park feature instances (F00048, F00049, F00075) is implemented as follows: 

1. S00224, S00296, S00298 assigns V00231, which values "Reservation Type" (AD0021) as "Park." 

2. S00225, S00297, S00299 assigns V00190, which values "Reservation Use Status" (AD0022) as "State." 

The attribution of the boundary line objects is implemented as follows: 

1. S00253 and S00266 assign V00166, which values "Delineation Status" (AD0013) as "Definite," to F00061 and 

F0007 6 respectively. 

2. S00255 assigns V00204, which values "Delineation Status" (AD0013) as "Indefinite," to F00061. 

The following Attribute Assigrunent records relate to this example: 

Attribute Assignment Table (Reservation and Boundary Line example): 

SKEY EFID AFID SKEY EFID AFID 

S00104 F00018 E00022 S00253 F00061 V00166 

S00105 F00018 T00002 S00254 F00066 E00024 

S00106 F00018 V00121 S00255 F00066 V00204 

S00107 F00018 V00006 S00257 F00075 E00018 

S00218 F00048 E00018 S00265 F00076 E00024 

S00222 F00049 E00018 S00266 F00076 V00166 

S00224 F00048 V00231 S00273 R00088 T00017 

S00225 F00048 V00190 S00296 F00049 V00231 

S00226 F00050 EOOOOl S00297 F00049 V00190 

S00227 F00050 TOOOlO S00298 F00075 V00231 

S00252 F00061 E00024 S00299 F00075 V00190 

Appendix B-43 

APPENDIX C 

DLG-E DATA MODEL IMPLEMENTED WITHIN THE 

SPATIAL DATA TRANSFER SPECIFICATION 

Section 

1. Data model component mappings C-1 

2. Mapping DLG-E to an SDTS data structure C-2 

APPENDIX C 

DLG-E DATA MODEL IMPLEMENTED WITIDN 

THE SPATIAL DATA TRANSFER SPECIFICATION 

This appendix describes how the components of the DLG-E data model may be implemented within SDTS. Since SDT~ 

is still undergoing review, several implementation issues are yet "to be resolved" (I'BR). Therefore, the content of this 

appendix should not be considered to be fmal. 

In the section of the main text entitled "A New Design," a framework for translating a set of data requirements into da•a 

model/structure/format constructs was presented Levels were defined which can serve as steps in the translation process. 

The first two levels, defming a data reality and a data model are covered in the section "Concepts of the DLG-E 

Design." This section, in conjunction with SDTS, is the next step in completing the translation process through the 

remaining two levels, data structure and file structures. 

Before proceeding with the data structure step, the implementation of DLG-E within SDTS requires an initial "data 

mapping" step at the data model component level. This process must occur for any agency or user-defined data model or 

structure to conform to SDTS. SDTS has its own set of data model components. The components of DLG-E must .first 

be mapped into SDTS model components. Only then can an SDTS data structure and file structure be selected. 

1. DATA MODEL COMPONENT MAPPINGS 

For the most part, DLG-E data model components have direct counterparts in SDTS. SDTS is more comprehensive in 

that it deals with graphic vector data and raster data, as well as topologically structured vector data. The DLG-E model 

is a clear topological vector data subset of SDTS. In only a few cases do the definitions of SDTS components need tn 

be qualified to match DLG-E. 

The data mappings outlined here do not include global (that is, header) data. The DLG-E data model does not explici•ly 

include them. Following the data model mappings, actual file structures will be outlined that will include SDTS globa1 

modules. 

Summary of data mapping equivalence table, DLG-E and SDTS model components: 

DLG-E Objects 

Feature object 

Linear graph/spatial objects 

Node 

Chain 

Polygon 

Point 

DLG-E Attributes 

Locational 

Nonlocational 

of feature object 

of attribute value 

DLG-E Relationships 

Topological 

Point-within-area 

All others 

SDTS Objects 

Feature implemented as a composite object 

Node 

Chain 

T-Polygon 

Entity point (qualified as wholely contained within one area) - TBR 

SDTS Attributes 

Location coordinates (often termed spatial addresses) 

Attribute related to composite object 

Secondary attributes 

SDTS Components 

Attribute with polyg~n foreign ID as attribute value - TBR 

Included in node, chain, and t-polygon object definitions and defined 

relations 
Nontopological 

Feature composed 

of element 

All others 

Composite-composed of -element relation; 

element ID's in the composite object record 

TBR 

2. MAPPING DLG-E TO AN SDTS DATA STRUCTURE 

SDTS has two possible data structure forms from which to choose: vector and raster. Because the DLG-E mcx:lel is 

fundamentally vector, that form will be outlined here. 

IMPLEMENTING DLG-E WITillN THE SDTS VECTOR FORM 

The following table summarizes the modules and vector-based object representations that might be used in the DLG-E 

Implementation. 

Module Tvpe 

Point-node 

Line 

Polygon 

Composite 

Attribute primary 

Attribute secondary 

Object Representation 

Entity point 

Area point 

Node 

Complete chain 

T-polygon 

Composite object 

Attribute primary module defines the primary 

attributes associated with a spatial element 

or object. 

Attribute secondary module defines the 

secondary attributes associated with values 

of primary attributes. 

Representation Code 

PG (fBR) 

PA 

PN 

LE 

PC 

FF 

The headings in the sections below have the following meaning: 

MNEMONIC: 

FULL NAME: 

Four-character mnemonic. The mnemonic will be left adjusted in the column for field name~ and right 

adjusted for subfield names. Mnemonics for primary field names will be flagged with an "* ." 

The full name of the field or subfield as used in the SDTS module specifications. 

DLG-E Point Within the SDTS Point-Node Module 

FIELD/SUBFIELD 

MNEMONIC FULL NAME (plus description if appropriate) 

*PNTS 

OBRP 

OBID 

SADR 

ARID 

Point-node 

Object representation ("PG" Entity point - TBR) 

Object ID 

Spatial address (locational coordinates) 

Area ID (TBR) 

C-2 An Enhanced Digital Line Graph Design 
FIELD/SUBFIELD 

MNEMONIC 

*PNTS 

OBRP 

OBID 

SADR 

LNID 

FIELD/SUBFIELD 

MNEMONIC 

*LINE 

OBRP 

OBID 

PIDL 

PIDR 

SNID 

ENID 

SADR 

FIELD/SUB FIELD 

MNEMONIC 

*POLY 

OBRP 

OBID 

LFID 

FIELD/SUBFIELD 

MNEMONIC 

*COMP 

OBRP 

OBID 

ATID 

FRID 

*ATPR 

DLG-E Node Within the SDTS Point-Node Module 

FULL NAME (plus description if appropriate) 

Point-node 

Object representation ("PN" node) 

Object ID 

Spatial address (locational coordinates) 

Line ID (This is a repeating field containing the ID's of the chains bounded by the node.) 

DLG-E Chain as Carried Within the SDTS Line Module 

FULL NAME (plus description if appropriate) 

Line 

Object representation ("LE" complete chain) 

Object ID 

Polygon ID left 

Polygon ID right 

S tartnode ID 

Endnode ID 

Spatial address (fhis is a repeating field containing the coordinates of the chain. The order 

of the instances of this field indicates the construction of the line in terms of vertices.) 

t.. 

DLG-E Polygon as Carried Within the SDTS Polygon Module 

FULL NAME (plus description if appropriate) 

Polygon 

Object representation ("PC" T -polygon) 

Object ID 

Chain foreign ID (This is a repeating field for carrying the chain ID's bounding the area.) 

~ 

DLG-E Feature ObJect as Carried Within the SDTS Composite Module 

FULL NAME (plus description if appropriate) 

Composite 

Object representation ("FF") 

Object ID 

Attribute ID (This is a repeating field containing the !D's of the primary attribute records 

associated with this feature object.) 

Foreign ID (This is a repeating field containing the !D's of the objects [other 

features, points, nodes, chains, and/or area] that are a part of this feature.) 

Attribute Primary (This is a separate module defming the primary attributes associated with, 

in this case, a feature object.) 

Appendix f:-3 



SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS 

Periodicals 

Earthquakes & Volcanoes (issued bimonthly). 

Preliminary Determination of Epicenters (issued monthly). 

Technical Books and Reports 

Professional Papers are mainly comprehensive scientific reports 

of wide and iasting interest and importance to professional scientists 

and engineers. Included are reports on the results of resource studies 

and of topographic, hydrologic, and geologic investigations. They also 

include collections of related papers addressing different aspects of a 

single scientific topic. 

Bulletins contain significant data and interpretations that are of 

lasting scientific interest but are generally more limited in scope or 

geographic coverage than Professional Papers. They include the results 

of resource studies and of geologic and topographic investigations, as 

well as collections of short papers related to a specific topic. 

Water-Supply Papers are comprehensive reports that present 

significant interpretive results of hydrologic investigations of wide 

interest to professional geologists, hydrologists. and engine<.'rs. The 

series covers investigations in all phases of hydrology, including 

hydrogeology, availability of v.rater. quality of water. and use of water. 

Circulars present administrative information or important scientific information of wide popular interest in a format designed for 

distribution at no cost to the public. Information is usually of short-term 

interest. 

Water-Resources Investigations Reports are papers of an 

interpretive nature made available to the public outside the fom1al 

USGS publications series. Copies are reproduced on request unlike 

formal USGS publications. and they are also available for public 

inspection at depositories indicated in USGS catalogs. 

Open-File Reports include unpublished manuscript reports, 

maps. and other material that are made available for public consultation 

at depositories. They are a nonpermanent form of publication that may 

be cited in other publications as sources of information. 

Maps 

Geologic Quadrangle Maps are multicolor geologic maps on 

topographic bases in 7.5- or 15-minute quadrangle formats (scales 

mainly 1:2-LOOO or 1:62,500) showing bedrock, surficial, or engineering geology. Maps generally include brief texts: some maps include 

structure and columnar sections only. 

Geophysical Investigations Maps are on topographic or planimetric bases at various scales: they show results of surveys using 

geophysical techniques, such as gravity, magnetic, seismic, or radioactivity, which reflect subsurface structures that are of economic or 

geologic significance. Many maps include correlations with the geology. 

Miscellaneous Investigations Series Maps are on planimetric or 

topographic bases of regular and irregular areas at various scales: they 

present a wide variety of format and subject matter. The series also 

includes- 7 .5-minute quadrangle photogeologic maps on planimetric 

bases that show geology as interpreted from aerial photographs. Series 

also includes maps of Mars and the Moon. 

Coal Investigations Maps are geologic maps on topographic or 

planimetric bases at various scales showing bedrock or surficial 

geology, stratigraphy, and structural relations in crrtain coal-resource 

areas. 

Oil and Gas Investigations Charts show stratigraphic information for certain oil and gas fields and other area~ having petroleum 

potential. 

Miscellaneous Field Studies Maps are mllticolor or blackand-white maps on topographic or planimetric basrs on quadrangle or 

irregular areas at various scales. Pre-1971 maps show bedrock geology 

in relation to specific mining or mineral-deposit p~ob1ems: post-1971 

maps are primarily black-and-white maps on vario·•s subjects such as 

environmental studies or wilderness mineral investigations. 

Hydrologic Investigations Atlases are multicolored or blackand-white maps on topographic or planimetric bases presenting a wide 

range of geohydrologic data of both regular a1d irregular areas: 

principal scale is 1:2-LOOO, and regional studies arr at 1:250,000 scale 

or smaller. 

Catalogs 

Permanent catalogs, as well as some others. giving comprehensive listings of U.S. Geological Survey publication~ are available under 

the conditions indicated below from the U.S. Geological Survey. 

Books and Open-File Reports Section, Federal Center, Box 25425, 

Denver, CO 80225. (See latest Price and Availability List.) 

''Publications of the Geological Survey, 1879-1961" may be 

purchased by mail and over the counter in paperbaC'k book form and as 

a set of microfiche. 

"Publications of the Geological Survey. 1962-1970" may be 

purchased by mail and over the counter in paperbaC'k book form and as 

a set of microfiche. 

••Publications of the U.S. Geological Surw~y;l971-1981" may 

be purchased by mail and over the counter in paperb1ck book form (two 

volumes. publications listing and index) and as a set of microfiche. 

Supplements for 1982. 1983, 1984, 1985, 1986, and for subsequent years since the last permanent catalog m~y be purchased by 

mail and over the counter in paperback book form. 

State catalogs. "List of U.S. Geological SP~vey Geologic and 

Water-Supply Reports and Maps For (State)," ray be purchased by 

mail and over the counter in paperback booklet form only. 

"Price and Availability List of U.S. Geohgical Survey Publications," issued annually, is available free of charge in paperback 

booklet form only. 

Selected copies of a monthly catalog "New Publications of the 

U.S. Geological Survey" are available free of charge by mail .or may 

be obtained over the counter in paperback booklet form only. Those 

wishing a free subscription to the monthly catalog ''New Publications of 

the U.S. Geological Survey" should write to ti.e U.S. Geological 

Survey, 582 National Center. Reston, VA 22092. 

Note.- Prices of Government publications listed in older catalogs, announcements, and publications may be incorrect. Therefore. 

the prices charged may differ from the prices in catalogs, announcements, and publications.