Reference for display files (position 29)
You can specify R in this position to use the reference function
of the i5/OS™ operating
system to copy the attributes of a previously defined named field (called
the referenced field) to the field you are defining.
Usage for display files (position 38)
Use this position to specify that a named field is an output-only, input-only, input/output (both), hidden, program-to-system, or message field.