The TDP identifier (tdpid) has the format TDPn, where n can be any of the following characters:
The default tdpid in the System Parameter Block (HSISPB and HSHSPB) is TDP0. To use a different tdpid, substitute the selected tdpid in the System Parameter Block.
Users can log on using either the full four-character TDP name, or just the suffix character of the name (such as A, B, 1, 2). The logon string without the full TDP name or suffix character is automatically assigned the TDP name in the System Parameter Block.