Preloaded Command Prompts

I want to create a command that will lookup and preload parameter
values if the value specified for the first parameter represent an
existing definition. This is similar to how the CHGJOBD and CHGUSRF
commands work. I know that I could wrap the process with a front-end
command to lookup the values and then display the prompted values.
However, I would prefer to do this with a single layer. Is there
something in the command definition that already lends itself to
performing this type of lookup functionality?

Sincerely,

Dave Clark