For the purposes of the Global Change Master Directory (GCMD), metadata is defined as: "Descriptive information that characterizes a set of quantitative and/or qualitative measurements and distinguishes that set from other similar measurement sets. Controlled keywords are essential within the metadata to provide a normalized discovery for data through 10 sets of controlled keywords, data-related services, climate diagnostics, etc.  and are required within the GCMD." (L. Olsen)

The metadata used by the GCMD is considered to be that set of attributes that are instrumental in helping users to determine if a data set meets their qualifications. The set of attributes (fields) and its associated syntax is known as the Directory Interchange Format (DIF) . It has evolved over the years and serves the user community in the discovery of Earth science data.

Additional metadata within the GCMD addresses data-related services (SERFs) and climate visualizations (CDs) created from Earth science data sets.

In addition to the Directory Interchange Format (DIF) standard, the Global Change Master Directory staff works with other groups involved with promoting standards and has cross-mapped its valuable set of fields to other formats to synchronize content. 

• The ISO 19115/TC 211 Geographic Information/Geomatics Metadata Standard
  • DIF to ISO 19115 Mapping
  • North American Profile of ISO 19115:2003, Geographic information - Metadata
  
  
• Federal Geographic Data Committee (FGDC) Content Standard for Digital Geospatial Metadata
  • DIF to FGDC Mapping
  
  
• ESRI Profile of the FGDC Content Standard for Digital Geospatial Metadata for Geospatial One-Stop (GOS) Portal
  • DIF to ESRI Profile of FGDC Mapping
  
  

• The Jakarta Lucene Search and Retrieval Protocol
• GCMD Lucene implementation

• The Dublin Core Metadata Initiative
  • DIF to Dublin Core Mapping

• The Australia New Zealand Land Information Council (ANZLIC)
  • DIF to ANZLIC Mapping

• The ADN (ADEPT/DLESE/NASA) metadata framework