Criteria for selecting user descriptors

When a user signs on, if the user structure does not exist, IMS selects a user descriptor to build the user structure.

IMS selects the user descriptor according to the following criteria:

1. An installation-written exit routine can select the name of the user descriptor (user ID, node name, or DFSUSER).
2. IMS looks for USERD, provided at logon. IMS also looks for a descriptor name (user ID, node name, or DFSUSER) that is specified in the USER descriptor field of the /SIGN or /OPNDST command.
3. IMS looks for a descriptor that has the same name as the user ID (installation-created user descriptor only). If IMS finds one, and an LTERM keyword is not specified in the descriptor, IMS creates a user structure and a single LTERM, both of which have the same name as the user ID.
4. IMS looks for a descriptor that has the same name as the VTAM® node (node user descriptor). If IMS finds one, and an LTERM keyword is not specified in the descriptor, IMS creates a user structure and a single LTERM, both of which have the same name as the VTAM node. However, no output security is associated with this user structure. Any user that signs on at a terminal can receive messages that are queued for that terminal.
5. IMS selects the default user descriptor, DFSUSER. IMS creates a user structure and a single LTERM, both of which have the same name as the user ID.