> For 8-bit, 16 maps to 7.5IRE which is the well understood legal black. Mapping 235 means they mapped peak to 110IRE.

Generally no -- in an 8-bit NTSC-M Rec. 601 system, 16 maps to E'Y = 0 at 7.5 IRE, and 235 maps to E'Y = 1 at 100 IRE. See https://www.poynton.ca/pdf/Poynton-1996-TechIntrDigiVide.pdf

The "16" digital black level is independent of the "7.5 IRE" analog setup. E.g. in Japan with an 8-bit "NTSC-J" Rec. 601 system, my understanding is that 16 still maps to E'Y = 0 which is now at 0 IRE, and 235 is still E'Y = 1 at 100 IRE.