UNIBUS M9312 ROM type identification

[JP Hindin]

Greetings;
My googlefu is failing me and I was wondering if someone might be able to 
help me identify one of the boot ROMs present in an M9312 bootstrap/term 
board. The board has three ROMs, an RX01 (042130), an RX02 (042131) and 
then a mystery code - 043127.

The M9312 ROM identification table does not list this ROM code - I suspect 
it _might_ be for a DSD combined 8" drive and Winchester disk box, but I'm 
under the impression this would appear as a DU device, and attempting to 
boot from DU gets an ILL CMD, suggesting otherwise. I tried all of the 
other possible mnemonics listed in the M9312 manual, so it doesn't appear 
to piggy-backing on any of those either.

My thanks;

 - JP