submaster

noun3

1. •
   [before a noun] A key that can open several locks, but fewer than a master key.

   • In an office, a submaster might open all doors in the accounting department; in an industrial facility, it might open all locks in the loading dock area. — 2004
2. •
   A copy of a master copy of a recording, generally kept for archival purposes.

   • Unlike cue or group information, submasters usually actively exist and don't need to be created. Methods for recording channel information into different submasters may vary between consoles. — 2013
3. •
   (historical) A secondary or subsidiary schoolmaster.