I was poking around on the Unix v7 man page archive
the other day, and
discovered to my delight that BCPL roff's request list was documented
Yes, it's the same spec, though reimplementated; there was no BCPL
compiler for the PDP-11.
Unfortunately, it was marked up in...BCPL roff
a man page, which hopelessly confused groff.
I edited the v7 manual and I believe I proofread every man page. How
could I have overlooked the misbehavior of the .li request*, which was
even then not in the reference manual's list of n/troff requests? On
closer examination, .li does appear in a condensed alphabetical list of
requests--and it appears in the source. But if Joe never described it,
it's no surprise that groff dropped it. It is totally unnecessary--a
bit of special pleading rendered obsolete by Joe's elegant invention
* .li causes the next line to be read literally, even if it begins
with a dot.