I like the idea of an rfc1345.tmac file, and would be happy to operate under the false assumption that it exists. I think it would be reasonable to abandon the old AT&T accent strings while we're at it, even though I have plenty of groff source that uses them.
Corollary 1: So that calls for abandoned strings don't just silently get ignored, warnings should be issued for unknown strings--preferably only once per distinct name. Corollary 2: If Corollary 1 is adopted, then for consistency warnings should be issued similarly for undefined macro calls and undefined escape sequences. Yours radically, Doug