Source:http://linkedlifedata.com/resource/umls/id/C1096774
MSH: Work consisting of written or printed communication between individuals or between persons and representatives of corporate bodies. The correspondence may be personal or professional. In medical and other scientific publications the letter is usually from one or more authors to the editor of the journal or book publishing the item being commented upon or discussed. LETTER is often accompanied by COMMENT.,NCI: A written message addressed to a person or organization.