Extensions and profiles
Extensions
The FGDC standard has been conceived to describe the generic characteristics of geospatial data across different disciplines. However, the FGDC standard foresees the needs of metadata producers to add elements to describe additional characteristics not covered in the base standard because relevant only for specific disciplines. For example, biologists might find useful to include elements to the FGDC metadata describing characteristics such as Taxonomy, Specimen, etc of some geo-spatial dataset that have biology emphasis. Metadata extensions are user-defined elements that describe information used by a specific discipline or organization. When adding a new element to the FGDC standard, it is absolutely important to verify that there isn’t an already existing element in the standard that meets this need. The official requirements and the basic semantics for the development of user defined extension are described in the Appendix D of the FGDC CSDGM Workbook.
The following are the simplest rules that a data set producer or a user community must follow when defining extended elements:
- An extended element must be described properly inside the hierarchical structure of the standard. It is important to locate the new extended element under a proper existing section and structure, if there is not a proper existing section, a new section and subsection must be defined. The existence of a new extended element must be described under the Metadata reference Information, within the Metadata_Extensions element.
- An extended element can not be nested under a data element.
- If standard elements are contained in compound elements, no existing components of the compound standard element must be changed.
- An extended element must not change the name, definition, domain, type of a standard element.
- An extended element may be defined as a compound element and can contain additional extended element and existing standard elements.
- Extended elements, like the standard element “Contact_information” can appear in several places in the metadata set.
Profiles
Specific user communities have the options to manipulate standards to develop profiles of the base standard that better meet their standards. Profiles are extended base standard by either adding metadata elements
Profiles are defined by the FGDC standards as:
"A subset of the metadata entities and elements of the base standard that describes the application of the Standard to a specific user community. A Profile permits modifications to the optionality or repeatability of non-mandatory elements and domains, where permitted, in the Standard. Profiles may also contain extended elements."
The following are the simplest rules that a data set producer or a user community must follow when defining a new profile:
- The new profile must include all the mandatory and mandatory-if-applicable elements of the base standard.
- New user defined extended elements can be added to the profile
- The new profile can not modify the name, definition and data type of the mandatory and mandatory-if-applicable elements of the base standard.
- A profile can only modify existing elements by imposing more restrictive conditions over the mandatory sand domain status of the elements. A profile will not permit anything that is not allowed by the base standard. Optional elements can be converted to mandatory, but not the opposite. The range type of domain of an element in the new profile can be smaller but not larger than in the base standard. A domain of free text can be replaced by a closed list of values.
For more information about in detail rules for creating and formalizing a profile refer to the Appendix E of the FGDC CSDGM Workbook.
Formalized profiles
Several profiles have been formalized through the FGDC standards process. In addition informal profiles can be created by metadata producer and used within a user community.
However, when possible, it is advisable to use profiles that have been recognized by FGDC standard process; this effort will avoid limitations to metadata usability across the global GIS community. Three instances of common formalized profiles are:
Content Standard for Digital Geospatial Metadata, Part 1:
Biological Data Profile
The objective of the profile is to provide a common set of terminology and definitions for the documentation of biological data through the creation of extended elements and a profile of the FGDC Content Standard for Digital Geospatial Metadata.
ESRI Metadata Profile
The ESRI Profile is intended to allow an item's properties to be automatically harvested and recorded in the metadata, to provide information in terms that are more familiar and relevant to ESRI software users, and to allow metadata records to contain graphics and files that describe the dataset. The extended elements also allow improved documentation of items that aren't specifically addressed by the FGDC standard.
RS (Remote Sensing) Metadata Profile
This profile defines content standards for additional information, not defined in the Metadata Content Standard, that are needed to describe data obtained from remote sensing. They include metadata describing the sensor, the platform, the method and process of deriving geospatial information from the raw telemetry, and the information needed to determine the geographical location of the remotely sensed data.
Shoreline metadata Profile
The Shoreline Metadata Profile provides the format and content for describing data sets related to shoreline and other coastal data sets.
Cadastral Data Content Standard
The Cadastral Data Content Standard is intended to support the automation and integration of publicly available land records information.
A list of all the FGDC formalized profiles can be found within the FGDC Metadata Profiles Web Site.
References
Heery, Rachel and Manjula Patel (2000) "Application profiles: mixing and matching metadata schemas". Ariadne, No. 25, September.
Available at: http://www.ariadne.ac.uk/issue25/app-profiles/intro.html
Hugh Aste, Rick Nyarady & Greg Mulholland (2004). Profile Definition for a Standardized Cadastral Model
Available at: http://www.fig.net/commission7/bamberg_2004/ppt/ts_02_04_astle_mulholland_nyar_ppt.pdf
Frondorf, A., M. B. Jones, and S. Stitt. 1999. Linking the FGDC Geospatial Metadata Content Standard to the Biological/Ecological Sciences Proceedings of the Third IEEE Computer Society Metadata Conference. Bethesda, MD.
Available at: http://www.computer.org/proceedings/meta/1999/papers/4/afrondorf.html
