What is the IDN?

The International Directory Network (IDN) evolved from the prototype NASA Master Directory (NMD) as part of the National Space Science Data Center (NSSDC) at NASA/Goddard Space Flight Center to promote the exchange of scientific data sets through the Catalog Interoperability (CI) project. In the summer of 1987, the CI Working Group (consisting of several U.S. Federal and international agencies) defined the type of information and level of detail that would be contained within the NMD. The first version of the NMD was released during that year. In 1989, the Committee on Earth Observation Satellites (CEOS) Data Working Group (DWG) established the CEOS International Directory Network (IDN) to foster the exchange of information among international agencies. In 1990, the Interagency Working Group on Data Management for Global Change (IWGDMGC) adopted the directory as a prototype to facilitate global change research - in response to the challenge by the Earth System Science Committee (ESSC). Thereafter, the NMD was renamed the Global Change Master Directory (GCMD) for its Earth sciences applications. In 1994, the GCMD project became part of the Global Change Data Center within the Earth Sciences Directorate at NASA/GSFC, where it still resides.

Today, the IDN is one of the largest public metadata inventories in the world. The IDN’s primary responsibility is to maintain a complete catalog of all NASA’s Earth science data sets and services. The project also serves as one of NASA’s contributions to the international Committee on Earth Observation Satellites (CEOS), through which it is known as the CEOS International Directory Network (IDN). The CEOS International Directory Network (aka the GCMD) metadata content for all of the NASA data set entries has been contributed to the GEOSS Portal and clearinghouse. The IDN is an international effort developed to assist researchers in locating information on available data sets. The directory provides free, online access to information for scientific data worldwide in the Earth sciences: geoscience, hydrosphere, biosphere, satellite remote sensing, and atmospheric sciences. The CEOS IDN Master Directory describes data held by university departments, government agencies, international government agencies, and associated organizations.

What is Role of GCMD at IDN?

The IDN, working through NASA's Global Change Master Directory (GCMD), holds more than 25,000 Earth science data set and service descriptions, which cover subject areas within the Earth and environmental sciences. The project mission is to assist researchers, policy makers, and the public in the discovery of and access to data, related services, and ancillary information (which includes descriptions of instruments and platforms) relevant to global change and Earth science research. Within this mission, the directory also offers online authoring tools to providers of data and services, facilitating the capability for making their products available to the Earth science community. In addition, citation information to properly credit data set contributions is offered, along with direct links to data and services. As an integral part of the project, keyword vocabularies have been developed and are constantly being refined and expanded. These vocabularies are also used in other applications within the broader scientific community. Users may perform searches through the Directory’s website using controlled keywords, free-text searches, map/date searches or any combination of these. Users may also search or refine a search by data center, location, instrument, platform, project, or temporal/spatial resolution.

The Interoperability (INTEROP) Forum (
The Interoperability Forum (Interop Forum) is designed to share suggestions for the Committee of Earth Observation Satellites' (CEOS) International Directory Network's (IDN) metadata content requirements, syntax specifications, and access considerations. The goal is to improve the use of the directory through its standards: the Directory Interchange Format (DIF) and the Service Entry Resource Format (SERF). In addition, suggested enhancements, corrections, or other issues may be raised through the Forum, which relate to any aspect of the website, including the use of the docBUILDER authoring tool.

How do I search the IDN?

Tutorial on New Search Functionality

What are the different types of metadata formats in the GCMD/IDN?
Where can I go to find information on recently released data sets?

The IDN places a listing of new DIFs or SERFs online through RSS.

Additional questions