In Hoc...

[P.Rhaenda]

Four-letter Latin acronyms (IHSV, SPQR, INRI) were commonly understood
and used as recently as decade ago in catechism and Latin classes
anyway.  And the Constantine conversion story has been a Sunday School
staple for centuries.  Somone has already mentioned the cigarette
connection. There's no need to look for any obscure source for this one;
I suggest it is common knowledge among Pynchon's cohort.

			Denarius