[TUHS] Any Surviving LIL Compilers/Code Artifacts?

[segaloco via TUHS]

So I'm doing a little bit of the footwork in prep for analyzing manual differences between Research, Program Generic, and PWB/UNIX, and found something interesting.

The LIL Programming Language[1] was briefly available as a user-supported section 6 command on Fifth Edition (1974) UNIX, appearing as a page but not even making it into the TOC.  It was gone as quickly as it appeared in the Research stream, not surviving into V6.

However, with Al Kossow's provided Program Generic Issue 2 (1976) manual[2] as well as notes in the MERT Issue 0 (1977) manual [3], it appears that LIL was quite supported in the USG Program Generic line, making it into section 1 of Issue 2 and staying there through to Issue 3.  lc(1) happens to be one of the pages excised in the transformation from PG Issue 3 to MERT Issue 0.

This had me curious, so I went looking around the extant V5 sources and couldn't find anything resembling the LIL compiler.  Does anyone know if this has survived in any other fashion?  Additionally, does anyone have any recollection of whether LIL was in significant use in USG-supported UNIX sites, or if it somehow made it into section 1 and spread around due to the state of use in Research at the time USG sampled userland out.

Finally, one little tidbit from P.J. Plauger's paper[1] stuck out to me: "...the resulting language was used to help write a small PDP-11/10 operating system at Bell Labs."  Does anyone have any information about this operating system, whether it was a LIL experiment or something purpose-driven and used in its own right after creation?

[1] - http://www.ultimate.com/phil/lil/
[2] - http://bitsavers.org/pdf/att/unix/6th_Edition/UNIX_Programmers_Manual_197601.pdf
[3] - https://www.tuhs.org/Archive/Documentation/Manuals/MERT_Release_0/Pgs%2001-38%20Unix%20Programmer's%20Manual%20for%20MERT.pdf