VTAM® uses internal translation to translate USS and TSO/VTAM user messages. These messages must be translated internal to VTAM so that they can be sent on either an SSCP-LU (for USS) or LU-LU session (for TSO/VTAM). For user messages, ISTVTMEU defines the U.S. English text that should be used for these messages. This text can be changed, providing a function similar to USS tables.