ASN.1: defining a grammar for the UMLS knowledge sources.

The unified Medical Language System (UMLS) project provides resources on an experimental basis to the research community. In 1995 the four UMLS Knowledge Sources have been provided in an additional data format, Abstract Syntax Notation One (ASN.1). The benefits of ASN.1 are that it provides a standard, formal grammar for complex data and allows exchange of that data in a way which is independent of the particular software and hardware environment in which the data are created and stored. The paper begins with an introduction to the ASN.1 standard itself. It continues with a discussion of the ASN.1 implementation of the UMLS Knowledge Sources and some of the consequences for the newly released UMLS Knowledge Source Server. It concludes with a discussion of some of the benefits of using ASN.1 encoded data.