The Evolution of GCMD Keywords — An instructive tale of data standards development and adoption

NASA established the Global Change Master Directory (GCMD) and supporting keywords in the early 1990s as part of implementing the GCMD through the Directory Interchange Format or DIF.  The GCMD was developed to support the launch of the huge and enduring satellite-based Earth Observing System (EOS). The primary intent was to catalog EOS and related data, but the keywords have been implemented in many different systems and adopted in varying ways by many different organizations around the world. This essay provides an ethnographic examination of how the keywords have evolved and been managed and how they have been adopted over the last few decades. It illustrates how semantic approaches have evolved over time and provides insights on how standards and associated processes can be sustained and  adaptable. Ongoing institutional commitment is essential, but so is transparency and technical flexibility. Understanding the different roles involved in standards creation, maintenance, and use of standards as well as the services that standards enable is also critical. It is apparent that semantic representations need to be mindful of different contexts and carefully define verbs as well nouns and categories. Understanding and representing relationships is central to interdisciplinary interoperability.