Unassigned characters

From: Steven Pemberton <steven.pemberton@cwi.nl> Date: Thu, 15 Dec 2022 10:40:46 +0000 Message-Id: <1671100226900.3349799283.413590541@cwi.nl> To: ixml <public-ixml@w3.org> · This archive was generated by hypermail 2.4.0 : Thursday, 15 December 2022 10:41:01 UTC

 > Unassigned: ~[C; L; LC; M; N; P; S; Z].

It occurred to me that Unicode has a class Cn "Unassigned". Unsurprisingly, 
there are no characters in the Unicode database with this class.
http://www.unicode.org/reports/tr44/#General_Category_Values

So presumably if we had a grammar

input: char*.
char: assigned; unassigned.
-assigned: -~[Cn].
unassigned: [Cn].

this should only output characters in the input that are not assigned 
Unicode characters.

For discussion at a call sometime.

Steven