# Presentation: 262517

## Content Standards for Digital Geospatial MetadataandISO 19115 Metadata

## What Are Metadata?

- "Data about data"
- Metadata describe the content, quality, condition, and other characteristics of data.

## Examples of Metadata

- Identification
- Title? Area covered? Themes? Restrictions?
- Data Quality
- Accuracy? Completeness?
- Spatial Data Organization
- Vector? Raster? Type of elements? Number?
- Spatial Reference
- Projection? Grid system? Coordinate system?
- Entity and Attribute Information
- Features? Attributes? Attribute values?
- Distribution
- Distributor? Formats? Media? Online? Price?
- Metadata Reference
- Metadata currentness? Responsible party?

**Notes:**
Metadata describe different aspect of data, including:

Identification -- What is the name of the data set?  Who developed the data set?  What geographic area does it cover?  What themes of information does it include?  How current are the data?  Are there restrictions on accessing or using the data?
Data Quality -- How good are the data?  Is information available that allows a user to decide if the data are suitable for his or her purpose?  What is the positional and attribute accuracy?  Are the data complete?  Were the consistency of the data verified?  What data were used to create the data set, and what processes were applied to these sources?
Spatial Data Organization -- What  spatial data model was used to encode the spatial data?  How many spatial objects are there?  Are methods other than coordinates, such as street addresses, used to encode locations?
Spatial Reference -- Are coordinate locations encoded using longitude and latitude?  Is a map projection or grid system, such as the State Plane Coordinate System, used?  What horizontal and vertical datums are used?  What parameters should be used to convert the data to another coordinate system?
Entity and Attribute Information -- What geographic information (roads, houses, elevation, temperature, etc.) is included?  How is this information encoded?  Were codes used?  What do the codes mean?
Distribution -- From whom can I obtain the data?  What formats are available?  What media are available?  Are the data available online?  What is the price of the data?
Metadata Reference -- When were the metadata compiled?  By whom?

## What Good Are Metadata?

- Organize and maintain an organization's internal investment in geospatial data.
- (Do you know what you've got?)
- Provide information about an organization's data to catalogues and clearinghouses.
- (Can you describe to someone else what you've got?)
- Provide information during a data transfer.
- (Can they figure out what you've done?)

## FGDC MetadataBackground

## FGDC Content Standards for Digital Geospatial Metadata

- Published standard in 1994
- Includes hundreds of elements, 199 of which could be valued as fields
- Many compound (grouping) elements
- Elements have structure, can be optional, and can be repeated

## Development of the Standards

- Summer 1992 - FGDC forum on metadata
- Fall 1992 - draft standard released for 51⁄2-month public comment period
- Summer 1993 - revised draft tested as part of the clearinghouse prototype; subsequent drafts provided in January, March, and May 1994.
- June 8, 1994 - FGDC approves the standards.

**Notes:**
Why and how was the standard developed?

Much data are developed by the geospatial community, and these data often can serve many applications.  The lack of an ability to identify what data exist, the quality of data, and how to access and use the data results in  wasteful duplication of effort occurs, and hinders improved cooperation.

During June 1992, the FGDC sponsored an “Information Exchange Forum on Spatial Data.”  Presentations were given on many aspects of metadata, including efforts to standardize metadata, uses of metadata, and systems used to provide metadata to users.  The need for a common definition of metadata in the community was identified.  The FGDC accepted the offer of ASTM to develop a draft standard.

The FGDC sponsored a public review of the draft from October 1992 to April 1993.  Many comments were received, and the draft was revised extensively.  The revised draft was tested as part of a prototype for the National Geospatial Data Clearinghouse.  Comments from this effort, a comparison of the draft with the U.S. Machine Readable Catalog (USMARC) standard and other documents,  and other activities resulted in additional refinements.

The FGDC approved the standard on June 8, 1994.  Executive Order 12906, “Coordinating Geographic Data Acquisition and Access:  The National Spatial Data Infrastructure,” requires Federal agencies to use the standard to document data that they produce beginning in 1995.

## Objectives (Does) 

- Supports common uses of metadata.
*internal investment - clearinghouse - transfer*
- Developed from the perspective of "what do I need to know about a data set?"
*availability - fitness - access - transfer*
- Provides a common set of terminology and definitions, and information about values to be provided.
- Identifies mandatory, mandatory if applicable, and optional data elements.

**Notes:**
The standard specifies the elements needed to support three major uses of metadata:  (1) to maintain an organization’s internal investment in geospatial data, (2) to provide information to data clearinghouses and catalogs, and (3) to provide information needed to process and interpret data transferred from another organization.

The standard defines the information required by a prospective user (1) to determine the availability of a set of geospatial data, (2) to determine the fitness of a set of geospatial data for an intended use, (3) to determine the means to access the set of geospatial data, and (4) to transfer the set of geospatial data successfully.

The standard specifies the information content for a set of digital geospatial data.  The standard establishes a common set of terminology and definitions for concepts related to metadata, including:

	the names of data elements and compound elements (groups of data elements) to be used,

	 the definitions of these compound and data elements, and 

	information about the values that are to be provided for the data elements.

The standard also specifies the elements that are mandatory (must be provided), mandatory  if applicable (must be provided if the data set exhibits the defined characteristic), and optional (provided at the discretion of the producer of the data set).

The standard defines a data set as a “collection of related data.”

## Evaluation Criteria

**Availability** — data needed to determine the sets of data that exist for a geographic location.
**Fitness for Use **— data needed to determine if a set of data meets a specific need.
**Access** — data needed to acquire an identified set of data.
**Transfer** — data needed to process and use a set of data.

## Objectives (Doesn't)

- The standards do not specify:
- the means to organize information in a computer system.
- the means to organize information in a data transfer.
- the means by which the information is transmitted, communicated, or presented to the user.

**Notes:**
The standard specifies information content, but not how to organize this information in a computer system or in a data transfer, or how to transmit, communicate, or present the information to a user.  There are several reasons for this approach:

There are many means by which metadata could be organized in a computer.  There include incorporating data as part of a geographic information system, in a separate data base, and as a text file.  Organizations can choose the approach which suits their data management strategy, budget, and other institutional and technical factors.

There are many standards and formats with which geospatial and related data are transferred.  Some include mechanisms permit the transfer metadata, some do not.  Decisions about how to accommodate metadata in a transfer must be made by the organizations that maintain these standards and formats.

There are a large number of ways by which to transmit, communicate, and present metadata.  Different metadata element will be valued by different users, or by one user for different tasks.  The Internet and other technologies are causing rapid change in means to providing information.  Many users continue to need or prefer metadata to be provided on physical media, including paper.  The standard allows information providers to use the techniques and forms which best meet the needs of their users.

Persons implementing the standard have recommended that some common approaches to implementing the standard be provided, especially for use with the National Geospatial Data Clearinghouse.  The FGDC invited recommendations about approaches that should be taken.

## Other Design Issues

- What is a "data set?"
- Existing standards.
- When's the best time to collect metadata?
- Digital and nondigital data.
- Data elements:
- Mandatory/conditional/optional.
- Structure and linkage.
- Number.
- Short names.
- Values that change frequently.

## Implementation Decisions

- What is a "data set?"
- When is the best time to collect metadata?
- Who is this for, anyway?
- Management — catalog — transfer.
- Details, details, details.
- “25¢ worth of metadata.”
- You're not responsible for the world (are you?).
- Legacy data and the future.

**Notes:**
The standard defines a data set as a “collection of related data.”  No statement is made about the granularity of data to which the standard should be applied, or limitations of how to apply the standard.  Many organizations start to implement the standard for a collection known as a “layer” or “coverage.”  Some organizations have a series of “layers” for which some elements, such as spatial reference, entity and attribute, and distribution information, are the same.  These elements are recorded once and  “inherited” by the member “layers” of the series.  Others are concerned about differences within a “layer,” and are implementing some elements, such as lineage information, for components of the “layer.”   These components “inherit” other information from the “layer” and “series” levels.  As long as the “mandatory” and appropriate “mandatory if applicable” are available to users, the metadata comply with the standard.  Decisions about what approach to take depend on the needs, budgets, and information strategies of an organization.

The best time to collect metadata is while the data are being developed, when the information needed for metadata is known.  Waiting until after the data are developed risks less accurate information being recorded and increased costs caused by searching for information.

There are many decisions to make about metadata.  Metadata serve many purposes, and not all purposes may need the same information.  Internal data management activities may require more information than a clearinghouse or transfer.  A huge number of details can be encoded in metadata; judgment is needed on what information is useful.  The costs and value of metadata, to both immediate and longer term operations, should be evaluated.  Judgment also is needed on deciding what information about source materials should be retained.

Documenting existing or “legacy” data can be daunting.  Details are long forgotten and costs can be high.  These concerns are valid, but care should be taken to avoid allowing issues related to legacy data to unduly influence the documentation of new data.

## Slide 13

## The FGDC Standard

- Content Standard for Digital Geospatial Metadata, 1994, revised 1998

**10/06/95**

## The Standards

## Elements of Definition

- Sections
- Compound Elements
- Data Elements

**Notes:**
The standard is organized in series of elements that define the information content for metadata to document a set of digital geospatial data.  

## Sections

- Main “chapters” of the standards.
- Composed of:
- Section definition.
- List of elements, definitions, types, and values.
- Information about what is mandatory and repeatable

**Notes:**
The standard is organized using numbered chapters called “sections.” 

Each section begins with the name and definition of the section.  These are followed by the component elements of the section.  Each section provides the names and definitions of the component elements, information about the types of values that can be provided for the elements, and information about the elements that are mandatory or repeatable.

## Sections of the Standards

- <----------- Metadata ----------->        <--------- Main Sections --------->               <--- Supporting Sections --->

**Notes:**
The standard has 11 sections numbered 0 through 10.

Section 0, “Metadata,” provides the starting point.  It is composed of the main sections of the standard.

Sections 1 through 7 are the main sections of the standard.

Sections 8 through 10 support other sections.  They provide a common method to define citation, temporal, and contact information.  These sections are never used alone.

## Compound Element

- A group of related data elements or other compound elements.
- All compound elements ultimately are comprised of data elements.
- _Form_:
- Compound element name -- definition.
- Type:  compound
- _Example_:
- Description -- a characterization of the data set, including its intended use and limitations.
- Type:  compound

**Notes:**
A compound element is a group of data elements and other compound elements.  All compound elements are described by data elements, either directly or through intermediate compound elements.  Compound elements represent higher-level concepts that cannot be represented by an individual data element.

The form for the definition of a compound element is:

	Compound element name -- definition.
		Type:  compound

The type of “compound” uniquely identifies the compound elements in the list of component elements.

An example of the definition of a compound element:

	Description -- a characterization of the data set, including its intended use and limitations.
		Type:  compound

As stated above, a compound element is a group of elements.  The composition of the element is needed to complete the example.  Using the syntax for the production rules:

	Description = Abstract  + 	Purpose  + (Supplemental Information)

which means that the compound element “Description” is composed of the elements “Abstract,” “Purpose,” and (optionally) “Supplemental Information.”

## Data Element

- A logically primitive item of data.
- Data elements are the things that you "fill in."
- _Form_:
- Data element name -- definition.
- Type:       (choice of "integer", "real", "text", "date", or
-                  “time")
- Domain:   (describes valid values that can be assigned)
- _Example_:
- Abstract -- a brief narrative summary of the data set.
- Type:	text
- Domain:	free text

**Notes:**
A data element is a logically primitive item of data.  The entry for a data element includes the name of the data element, the definition of the data element, and a description of the values that can be assigned to the data element.

The form for the definition of a data element is:

	Data element name -- definition.
		Type:       (choice of “integer”, “real”, “text”, “date”, or “time”)
		Domain:  (describes valid values that can be assigned)

The information about the values for that data elements include a description of the type of value, and a description of the domain of values.  The type of the data element describes the kind of value to be provided.  The choices are “integer” for integer numbers, “real” for real numbers, “text” for ASCII characters, “date” for day of the year, and “time” for time of the day.

The domain describes valid values that can be assigned to the data element.  The domain may specify a list of valid values, or restrictions on the range of values that can be assigned to a data element.

An example of the definition of a data element is:

	Abstract -- a brief narrative summary of the data set.
		Type:       text
		Domain:  free text

## Data Element — Values

- The **domain** of values for a data element:
**may be specified only by type**.  In these cases, the domain is described by the word "free" followed by the type (for example, free integer, free text).
**may be specified by a list **of values, **references **to a list of values, **or a range **of values.
**may be partly specified by a set of values, followed by the "free" convention**.  In this case, values should be selected from the provided set; if no value is adequate, the user may provide one.

**Notes:**
The domain of values for a data element:

may be specified only by type.  Any values that can be represented by the type of the data element can be assigned.  These domains are represented by the use of the word “free” followed by the type of the data element (that is, free integer, free real, free text, free date, free time).  For example:

	Abstract -- a brief narrative summary of the data set.
		Type:       text
		Domain:  free text

may be specified by a list of values, references to a list of values, or a range of values.  The value assigned must be selected from the domain.  For example:

	Progress -- the state of the data set.
		Type:       text
		Domain:  “Complete” “In work” “Planned”

may be partly specified by a set of values, followed by the “free” convention.  The value assigned should be from the domain provided if possible.  If a needed value is not available, providers may create and assign their own value.  For example:

	Depth Distance Units -- units in which depths are recorded.
		Type:       text
		Domain:  “meters” “feet” free text

  A created value should not redefine a value provided by the standard.

## Data ElementForms for Special Values

- The standards specify the forms of four types of values:
- Calendar dates
- Time of day
- Latitude and longitude
- Network addresses and file names

## ISO 19115 - Metadata

- Draft International Standard

**10/06/95**

## Metadata - Next Generation

- International consensus being built on structured metadata within a broader Geomatics Standard under ISO Technical Committee 211(TC 211)
- ISO 19115 (Committee Draft) reflects FGDC, CEN TC 287, ANZLIC, and other inputs
- Also specifies content guidance (field vocabulary and structures), like FGDC

## Convergence

- FGDC

- others

- TC287

- ANZLIC

- ISO
- TC 211
- 19115

## So What’s New?

- ISO standard permits inclusion of normative and informative annexes
- Metadata Standard will support catalog and full use via Profiles
- Informative annex specifies Clearinghouse services using Z39.50 and definition of metadata in XML

## ISO 19115 Essential Profile

- Intended primarily for use in describing spatial data sets for discovery
- Includes approximately 50 fields
- Covers the “who,” “what,” “when,” “where,” “why,” and “how” topics better than FGDC minimum mandatories
- May not be adequate for detailed description requirements

## ISO 19115 Full Metadata

- Includes catalog elements and structures
- Provides conditional detail in excess of FGDC metadata, including special coverage of raster and imagery information
- Largely conditional and optional elements and structures
- Will look familiar to FGDC users

## How does ISO affect me?

- National Profiles can take elements, make Optional become Conditional or Mandatory, and add additional elements
- National profiles must be consistent and use the same core structures for interoperability internationally
- Metadata software providers will migrate to support ISO 19115 content as it becomes available