Doubt about Progress 4GL

I'm new to development progress, and I'm having trouble understanding what this snippet does:

define variable cRunFile as character no-undo initial "gpldnfbr.p".

        {us/gp/gpmnp02.i cRunFile 10 """(input p_oid_lgdd_det,
                                         output p_exclude_app)"""}

I asked for a little help here and my supervisor told me it's a hook that calls another program, but I was still in doubt, it was not very clear, you know.