Implementation-defined character set

[ruv]

Rationale/clarification for implementation-defined character set is wanted:

This draft never fails to amaze in what it won't commit to. 3.1.2.2 is the first time implementation-defined character set is mentioned (out of 6 references in the document), yet its not discussed before that nor any rationale. They state ASCII is used, of which 0..31 are well defined controls including DEL, so how / when / why would you have an implementation-defined character set - maybe some rationale for 3.1.2, 3.1.2.1, 3.1.2.2 might help, for example:

   An `implementation-defined character set` can be any character set where 7-bit ASCII is a proper subset.
   For example UTF-8 encoding, Extended ASCII, Latin1 to name a few.

Originally posted by @SirWumpus in ForthHub/discussion#121 (reply in thread)