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Global Change Master Directory (GCMD) Keywords are a hierarchical set of controlled Earth Science vocabularies that help ensure Earth science data, services, and variables are described in a consistent and comprehensive manner and allow for the precise searching of metadata and subsequent retrieval of data, services, and variables. Initiated over twenty years ago, GCMD Keywords are periodically analyzed for relevancy and will continue to be refined and expanded in response to user needs. The categories of GCMD Keywords are as follows.

• Earth Science Keywords                                                                 
• Earth Science Services Keywords            
• Data Centers                                             
• Projects                                                     
• Instrument/Sensors
• Platforms/Sources                    
• Locations
• Horizontal Data Resolution
• Vertical Data Resolution
• Temporal Data Resolution
• URL Content Types
• Chronostratigraphic Units
  
  

To submit a keyword request (addition or modification) the submitter should:

1. State the proposed keyword
2. Provide a definition of the keyword
3. State the rationale for the keyword addition or modification

4. Review the keyword requirements (criteria used when determining what constitutes a well-curated keyword list)
   

5. Verify that the keyword does not already exists by checking the keywords in the Keyword Directory and search for the keyword

Once the above steps have been completed, submit the request to support@earthdata.nasa.gov. or post to the forum.The submitter will be notified of their submission status and when the keyword change has been made.

Other keyword issues/questions should be posted to the keyword forum.

Fast-Track Keywords:

• An expedited review process (less than five business days) for proposed additions and changes that are small and have little or no impact on other users and metadata providers.

Full-Review Keywords

• The full review process for proposed GCMD keyword changes is a review process facilitated by the ESDIS Standards Office (ESO) with input from subject matter experts drawn from the user and provider communities. These reviews take longer (1-2 keyword releases a year) to complete and are used for GCMD keyword changes or changes that have a large impact on existing users.

The keyword submitter will be notified whether their keyword is considered a fast-track or full review.

The GCMD Keywords are accessible via:

• GCMD Keyword Directory (Download in CSV Format)

• RESTful API Service 

  • RESTful API Service Documentation