Multics Execution Environment (2014)
multicians.org
multicians.org
I'm pretty sure you can grep the sunos sources and you'll find a bunch of LMXXX in the file system and a few in the VM system (LM being my initials).
I suspect everyone here knows but just in case, XXX in a comment in the kernel indicates something that you think needs to be fixed, it's kind of a "we haven't hit this issue yet but we will".