(Information literacy) may concern itself with a mastery of processes.
A student may demonstrate mastery of a field of specialization.
A mastery can be constituted-of-or-filled-with (tax law-its practice).
An advanced degree may reflect a mastery of (tax law-its practice).
A mastery may be demonstrated to satisfaction of a (dissertation director).
A mastery of a native language may be accepted as fulfilling a requirement.