Medical Subject Headings
ASCII MeSH, 2015. Documentation and Availability
1. ASCII MeSH
ASCII MeSH contains all data that were present in ELHILL MeSH,* including cross-references and scope notes. Descriptions of the data elements in each file are available for each of the three record types:
- Descriptor Data Elements
- Qualifier Data Elements
- Supplementary Concept Records (formerly Supplementary Chemical Records), Data Elements
See MeSH ELHILL Format Document (PDF format) for an additional description of the data elements, including most of those found in the ASCII MeSH file. Note changes effective with the fourth-quarter 1999 update. *Note that ELHILL MeSH is no longer in production.
2. Restrictions on use
There is no charge. Use of the ASCII MeSH file data is subject to conditions which are detailed in the Memorandum of Understanding.
The data for Descriptors and Qualifiers are updated annually and users of the data are encouraged to obtain the new year's data. Any changes made mid-year are included in the weekly update of ASCII MeSH files.
Supplementary Concept Records (formerly Supplementary Chemical Records) are updated at NLM on a daily basis. The current file in ASCII MeSH is updated weekly and is coordinated with 2015 MeSH descriptors so that the data elements that require a descriptor MH value, such as the HM element, have been updated to match a descriptor in 2015 MeSH. New records will be added to ASCII MeSH periodically.
4. File format
Each MeSH record is indicated by a separate line, preceding the record, consisting of the string
Each element or occurrence is contained on a single line. Each line contains an element name and value, for example,
MH = Appendicitis
The same is true for longer, free-text fields such the Annotation and Scope Note. (The longest occurrence/line in the files is in the descriptor file and is 1124 characters.)
For data elements that are multiple-occurring, each element occurs on a separate line, for example, the MeSH Tree Number:
MN = E05.200.500.607.790
MN = E05.200.500.620.670.620
Most data in ASCII MeSH files are in 7-bit ASCII format. However, we now have a small number of non-English entry terms having characters identified by a diacritic mark, for example, "Carbocaïne", a French trade name for the anesthetic Mepivacaine. (Note the small "i" with dieresis, known in French as the tréma.) These characters are encoded in Unicode UTF-8 format and will be correctly displayed by UTF-8 applications. (The previous will also display correctly since 7-bit ASCII encoding is a subset of UTF-8.) Otherwise they may appear differently in different displays.
The file extensions are .bin rather than .txt so that Web browsers will prompt to save rather than automatically trying to display the relatively large text files (up to 89MB). The lines will usually be transmitted with only a line feed character (decimal 10) and not also a carriage return (decimal 13). Please contact the MeSH Section at the address below if you have questions.
5. Contents of files - 2015 MeSH
Files updated weekly. Counts as of September 8, 2014.
|Record Type||Total Records||Total Terms||File Size||Bytes|
1 Formerly Supplementary Chemical Records.
6. ContactFor questions concerning distribution, format, etc., contact:
Medical Subject Headings
voice: 301-496-1495; FAX: 301-402-2002