Skip Navigation Bar

Unified Medical Language System® (UMLS®)

Metathesaurus Data Files

The Metathesaurus consists of forty data, metadata, and index files. The data files listed below contain information obtained from the source vocabularies. Concept Unique Identifiers (CUI) link concept data across files. The table below illustrates what information populates each data file. Click on the file name to see a sample of the data in that file.

Metadata File Name Contents
MRCONSO.RRF Names, Synonyms, Terms, Term Types, Codes
MRREL.RRF Relationships
MRHIER.RRF Hierarchies
MRSAT.RRF Attributes
MRDEF.RRF Definitions
MRMAP.RRF Mappings
MRSMAP.RRF Simplified Mappings
MRSTY.RRF Semantic Types

In addition to the data files two other types of files are produced with each Metathesaurus release.

Index files are produced to help developers build applications that search for specific words or groups of words. For example, the index file MRXNW_ENG.RRF connects words to all related strings, terms, and concept identifiers.

Metadata files contain information about each specific release of the Metathesaurus including its sources and files. For example, MRFILES.RRF contains a listing of all files in a Metathesaurus subset with a brief description and a listing of all rows and columns.

Subsets may include files with a size of 0 bytes. Some files may not be included with a subset. For example, MRXW_DUT.RRF will only be included in a subset that contains Dutch language terms.

< Previous Section | Next Section >