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Re: Combining characters (was: Re: [idn] hostname historyhell)

(resent after correcing some formatting error)
 
Does a combining sequence inherit the bicameral  characteristic of the leading letter ?  

For example, 

<A acute> can be lowercased into <a acute> ?  Then, <A><acute> ==> <a><acute> ?
<A><acute><diaeresis>... ==> <a><acute><diaeresis>... ?  I am not sure whether it can be.

Can <I><dot-above>   be lowercased into <i><dot-above> or not?
<I dot-above> has no combined form <i dot-above>, but has <i> as its lowercase form
due to its language context in turkish and azerbaijani.
Is this case just an exception ?

Soobok Lee
----- Original Message -----
From: Soobok Lee
Sent: Sunday, November 25, 2001 1:32 PM
Subject: Re: Combining characters (was: Re: [idn] hostname historyhell)

Does a combining sequence inherit the bicameral  characteristic of the leading letter ?   

For example,  

 can be lowercased into  ?  Then,  ==>  ?
... ==> ... ?  I am not sure whether it can be.

Can    be lowercased into  or not?
 has no combined form , but has  as its lowercase form 
due to its language context in turkish and azerbaijani.
Is this case just an exception ?

Soobok Lee


----- Original Message ----- 
From: "Eric A. Hall" 
To: "Kenneth Whistler" ; ; 
Sent: Friday, November 23, 2001 1:33 AM
Subject: Re: Combining characters (was: Re: [idn] hostname historyhell)


> 
> "Eric A. Hall" wrote:
> 
> > The specific concern I had is already addressed in nameprep so there
> > is no need for the exception.
> 
> What I am concerned with is the use of domain name which consist entirely
> of punctuation, or in this case, which consist entirely of combining
> marks. These represent a rules problem with the principles behind the
> "safe-set". EG, we forbid domain names like ````````.com using U+0060, but
> ````````.com may be legal if the combining character U+0300 is used
> instead.
> 
> I get lost in the shrubbery of specs, so can somebody tell me whether or
> not this is a valid concern? I can't tell for certain what happens at the
> end of nameprep with such a label.
> 
> If this is a problem, a solution might be to change the prohibition
> against leading hyphen to a prohibition against leading hyphen and
> combining characters.
> 
> -- 
> Eric A. Hall                                        http://www.ehsco.com/
> Internet Core Protocols          http://www.oreilly.com/catalog/coreprot/
>