Re: [idn] Prohibit CDN code points

[DougEwell2@cs.com]

In a message dated 2002-01-22 1:56:56 Pacific Standard Time, 
tsenglm@cc.ncu.edu.tw writes:

> TC/SC character equivalence mapping is similar to  the mapping of  UNICODE
> Alphabet  map  it to its counterpart of ASCII  alpnabet .

No, it isn't.  Stop saying that.

ASCII uppercase/lowercase mapping is straightforward and unambiguous, and can 
be done one character at a time with NO lexical analysis (at least for 99% of 
all languages that use it; Turkish and Azeri do have exceptions).

TC/SC is NOT one-to-one for all characters.  It is for many, but nowhere near 
99% or 95%.  If you implement any sort of TC/SC mapping you MUST figure out 
how to handle the many-to-one and one-to-many cases, and this is where we 
have all been balking.  Users will not understand or accept that "only some" 
of the TC and SC characters are mapped to each other.

-Doug Ewell
 Fullerton, California