You can code LU exit routines to specify the LU name used to represent the client. You can optionally return a USS table name (3270 or SCS format) or an Interpret table name to be used by Telnet. The entry point name must match the routine name specified as the LUGROUP group name. Each LU exit routine specified must be assembled and link-edited as a stand-alone load module.
The LU exit can be driven multiple times. If the LUNAME returned by the exit cannot be registered, the exit is driven again for a different LUNAME. If the same name is returned, the connection fails. If a different name is returned, it is registered. If registration fails for the second name, the exit is driven a third time, and the no additional retry flag is activated. If the second name is again returned, the connection is terminated. If a third name is returned, registration is attempted again. If registration fails, the connection is terminated.
The LUNAME exit can be mapped as GENERIC or SPECIFIC. If both mappings are present, and the client presents Telnet with an LUNAME, the SPECIFIC mapping is attempted. If this attempt fails, the GENERIC mapping is also attempted. This conforms with the process used when TELNET assigns LUNAMEs.