TS applications (clients with partner type APPLI or SOCKET that communicate via the UTM Socket Protocol (USP) in case of partner type SOCKET) behave similarly to terminals:
If there is no sign-on service, the TS application receives message K001 if the message destination PARTNER was assigned to this message; see the description of the KDCMMOD tool in the openUTM manual “Messages, Debugging and Diagnostics on BS2000 Systems”.
The TS application can then start a service by transferring a TAC, and possibly a message, to the UTM application. In this case, the first 8 characters of the message are interpreted as the TAC. If the TAC is shorter than 8 characters, it must be separated from the message by blanks.
If a sign-on service is performed, this service determines the next step. The sign-on service can either start a service directly to send a message to the TS application. In the latter case, the next message must contain a TAC in the first 8 characters, i.e. the same applies as when no sign-on service is used (see above).
Once the service has terminated, the next service can be started.