You can list an RMS definition file with the following command:
c:\> pdef deffile
Deffile is the name of the RMS definition file and produces output like the following:
Contents of file definition file def\mag
File organization method: indexed, reusing deleted records
Primary key ordering method: btree
Duplicate key handling method: none
Primary key fields: magazine
Secondary key 1 fields: title
Secondary key 2 fields: publisher, title
Field Type Size Elem Description
magazine string 16 1 magazine code
key alias 0 1 alias for magazine
publisher string 36 1 publisher of magazine
title string 36 1 magazine title
subscribers real 8 1 number of subscribers
rates money 8 3 rates for 1, 2, & 3 years