Related Concepts

You need to understand:

What the caller of the SSI function code 54 must code and what the caller expects to receive. See Request Subsystem Version Information Call — SSI Function Code 54 for a description of this Request Subsystem Version Information call from a calling program's point of view.
What the format of the IEFSSVI functional extension is as defined in Request Subsystem Version Information Call — SSI Function Code 54.