Expand fully the payroll schema with pgm RPDASC00 using sel.input
schema = main schema name
Schema type = C for payroll (T for time eval)
all other fields = '*'.
Execute
Search for /XXX. This gives the places where the search string appears in the schema pcrs.
It will not show if a function creates it.
To find that, run payroll with log.
Expand the top node of the pay period where you found the w/t /XXX in RT.
Search for /XXX. The first time it appears in output will indicate where it was created.