The Meta-1.2 engine: a refined strategy for linking biomedical vocabularies

This paper presents a preliminary description of the database schema and associated procedures that are the foundation for the "engine" that will produce Meta-1.2. Meta-1.2 is the next incarnation of the Metathesaurus, which is one of the principal components of the National Library of Medicine's Unified Medical Language System (UMLS). We use the word "engine" as a generic term that includes a database and the programs that operate on it. While this design builds heavily upon previous work, it incorporates some major changes in philosophy. A major hypothesis is that the simple representation described here is suitable for any controlled vocabulary in the biomedical domain. Indeed, this hypothesis is central to a strategy for producing future versions of the Metathesaurus and for supporting collaboration with people who wish to contribute additional terms and relationships to the Metathesaurus. Another change involves the representation of classes and relationships. The revised database schema includes an explicit representation of the source or "authority" for relationships, which is analogous to the way that the sources of terms have been represented since the first version of the Metathesaurus. A sequence of steps utilizing the new representations to produce the Metathesaurus is presented.