FEDERAL GEOGRAPHIC DATA COMMITTEE PHONE: 703-648-5514

U.S. GEOLOGICAL SURVEY, 590 NATIONAL CENTER FAX: 703-648-5755

RESTON, VIRGINIA 20192 HTTP://WWW.FGDC.GOV EMAIL: GDC@USGS.GOV

March 1997

Geospatial Metadata

WHAT ARE METADATA?

Recognize this? It is the food

label required by the Food and

Drug Administration on all food

packaged and transferred from

one place to another. As a

nation, we have been putting

some form of labels on our food

since 1913. Today, this label,

with its mandatory and

voluntary components, tells the

consumer everything they need

to know to make a decision

about the packaged food's

ingredients and nutritional

content. Using this label the

consumer can make an informed

decision about the product=s

fitness for use or consumption.

Sound familiar? Just as food is our body's fuel, spatial

data is the fuel of the GIS. How do you determine the

"really good stuff" from the "junk food"? How do you

know if the spatial data is "good" for your system?

The Content Standards for Digital Geospatial

Metadata were adopted by the Federal Geographic

Data Committee (FGDC) to label geospatial datasets.

Like a company whose product is food, the metadata

standard documents the characteristics of data so that

consumers can determine the data's fitness for their

purpose.

WHY METADATA?

The major uses of metadata are:

$ to help organize and maintain an

organization's internal investment in spatial

data,

$ to provide information about an

organization's data holdings to data

catalogues, clearinghouses, and brokerages,

and

$ to provide information to process and

interpret data received through a transfer

from an external source.

THE STANDARD

What do we need to know about our datasets? The

standard provides a common set of terminology and

definitions for the documentation of geospatial data,

including data elements for the following topics:
Identification Information C basic information about

the data set. Examples include title, geographic area

covered, currentness, and rules for acquiring or using

the data.

Data Quality Information C an assessment of the

quality of the data set. Examples include positional

and attribute accuracy, completeness, consistency,

sources of information, and methods used to produce

the data. Recommendations on information to be

reported and tasks to be performed are in the Spatial

Data Transfer Standard (Federal Information

Processing Standard 173 - 1992).

Spatial Data Organization Information C the

mechanism used to represent spatial information in the

data set. Examples include the method used to

represent spatial positions directly (such as raster or

vector) and indirectly (such as street addresses or

county codes) and the number of spatial objects in the

data set.

Spatial Reference Information C description of the

reference frame for, and means of encoding,

coordinates in the data set. Examples include the

name of and parameters for map projections or grid

coordinate systems, horizontal and vertical datums,

and the coordinate system resolution.

Entity and Attribute Information C information about

the content of the data set, including the entity types

and their attributes and the domains from which

attribute values may be assigned. Examples include

the names and definitions of features, attributes, and

attribute values.

Distribution Information C information about

obtaining the data set. Examples include a contact for

the distributor, available formats, information about

how to obtain data sets online or on physical media

(such as cartridge tape or CD-ROM), and fees for the

data.

Metadata Reference Information C information on

the currentness of the metadata information and the

responsible party.

The standard has sections that specify contact

information for organizations or individuals that

developed or distribute the data set, temporal

information for time periods covered by the data set,

and citation information for the data set and

information sources from which the data were

derived.

The standard does not specify how this information is

organized in a computer system or in a data transfer,

nor the means by which this information is transmitted

or communicated to the user. At this point in time,

these formats are optional.

ADDITIONAL INFORMATION

The standard and other metadata materials, along with

the implementation guidelines for the clearinghouse, are

available from the FGDC Secretariat at the above

address or from the FGDC server connected to the

Internet via: Anonymous FTP

Metadata - www.fgdc.gov under the subdirectory 

/pub/metadata

Clearinghouse - www.fgdc.gov under the subdirectory 

/pub/clearinghouse

The README files in the subdirectories give detailed

information about the available files.

FGDC Web Server <http://www.fgdc.gov/>