As far as I know there's no way to change the base character set or quoting
character in a mnemonic stream. If there's a problem with specifying this
stuff as embedded information in the charset parameter let's move it to
another optional pair of parameters (mnemonic-base and mnemonic-quote?)
and give reasonable default values for them.
There is a family of mnemonic character sets defined in RFC-CHAR.
But only one of these character sets are allowed in RFC-XXXX
according to the Santa Fe decisions, namely MNEMONIC+ASCII+38
also known simply as MNEMONIC.
For consenting adults, the way to use other character sets,including
mnemonic character sets, are to use the character set names defined
in RFC-CHAR.
Keld