The MVS™ Message Service translates VTAM® messages using message skeleton files for particular languages. MMS finds a skeleton file matching the language requested and then searches for the message and returns the text from the skeleton file.

VTAM provides a base U.S. English message skeleton file named ISTVTMEU. This file contains all VTAM messages including USS, TSO/VTAM, and logon manager messages. The way in which ISTVTMEU is used depends on whether the translation of the message occurs internally or externally to VTAM.