ok, so i didnt know what MOS stood for so I lookied it up. is there anything that doesn't fall under MOS? seems like a ranking system or something. I dunno, im sure im waaaay off.
http://www.uspharmd.com/usmc/cgi-bin/mos.cgi
0161 POSTAL CLERK
0205 TACTICAL INTELLIGENCE OFFICER
0300 BASIC INFANTRYMAN
3051 WAREHOUSE CLERK
4641 COMBAT PHOTOGRAPHER
5524 MUSICIAN
5526 MUSICIAN, OBOE
5528 MUSICIAN BASSOON
5534 MUSICIAN CLARINET
5537 MUSICIAN SAXOPHONE
5541 MUSICIAN TRUMPET
5543 MUSICIAN BARITONE HORN/EUPHONIUM
5544 MUSICIAN HORN
5546 MUSICIAN TROMBONE
5547 MUSICIAN TUBA AND SOUSAPHONE
5548 MUSICIAN ELECTRIC BASS
5563 MUSICIAN PERCUSSION (DRUMS, TIMPAN
5565 MUSICIAN PIANO OR GUITAR
5566 MUSICIAN GUITAR
9991 SERGEANT MAJOR OF THE MARINE CORPS