The ISTDEFIN and IOS502I command lists are designed to work together. However, you can call these command lists with your own functions and routines.

For example, you can write a command list that is invoked when NetView® or VTAM® startup completes. This command list can determine all VTAM-supported devices not currently used by VTAM. This command list can check all possible devices and then call the ISTDEFIN command list to build the definitions and activate the devices.