rfc1345.tmac is a great contribution. I hope to see 1. inclusion in the standard groff distribution.
2. the gitlab comment "Added \[Eu], \[=R], \[=P] from Vim digraph table." inserted in the file 3. A section groff_mrfc1245 in man7. It can be very short. Tell what it is; and refer readers to the file itself to see the 1696 glyphs it defines. Doug