[3] Key to character mapping "rfc1345-mnemonics" (2016-07-18 22:07:15 +09:00) https://chars.suikawiki.org/keys/rfc1345-mnemonics

[4] #387397 - screen should support digraphs for RFC1345 two-character mnemonics - Debian Bug report logs, 2023-07-16T12:38:14.000Z https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=387397

[5] vis/vis-digraph.c at master · martanne/vis · GitHub, 2023-07-16T12:39:08.000Z https://github.com/martanne/vis/blob/master/vis-digraph.c

[6] >>5 PUA も含めて漢字以外はすべて実装されている模様。