70-20274-15 - this is a DEC part number for ordering the Language rom; based on the 100A MB picture, the actual part number written on the rom is
LM8402
092E4
this translates to:
23-092E4, burned on 1984 week 2 (what exactly LM means I'm not sure, guessing maybe 'local manufacture' i.e. burned from a .hex file to a rom in one of the many DEC 'branch' service centers?)
LN