Lexical items are collected into unit records containing morphological, syntactic and spelling information about each item. The lexicon will contain over 125,000 lexical items in 119,000 records in the 1999 UMLS release.
Morphological information includes full inflectional information about each item.
A data base of derivational relationships is also maintained with the lexicon. Morphological and spelling information is important for matching of lexical items and forms a major part of the capability of the Lexical tools. Syntactic information includes verb complement patterns for verbs and sequencing information for adjectives. Verb complement information is central to analysis of sentence structure. Lexicon building tools have been used to facilitate lexicon building and maintain the consistency of the lexicon.