Geographical metadata models
In geographical information, metadata were first defined to support data exchange. Later on, metadata models were proposed to describe geographical data sets for cataloging purposes. In all these models, metadata information is organized into quite similar packages.
An early model, which has been partly reused by the next generations, is the Content Standard for Digital Geographic Metadata from the Federal Geographic Data Committee (FGDC CSDGM). The FGDC packages are: identification, quality, spatial properties, spatial reference system, entities and attributes, distribution, and metadata reference. The identification package contains the following elements: textual description, temporal and spatial extent, keywords, contact, access constraints, and technical information.
Organizations dedicated to normalization have also proposed metadata models for geographical data: the CEN TC287 in Europe and the ISO TC211 at an international level.
The CEN TC287 has led to a pilot implementation: the Geographical Data Digital Directory. It is a simple model that has been systematically documented for most geographical databases in Europe. Its elements are defined on the EuroGeographics GDDD Website (http://www.eurogeographics.org/gddd/INDEX.HTM) as follows:
• Overview: textual description, contact information (organization and individual)
• Commercial Information: geographical extension, conditions of sale, restrictions of use, format, etc.