HYPHEN-MINUS

Patrik Fältström patrik at frobbit.se
Tue Jul 28 17:20:52 CEST 2009


See the latest discussion with subject "CONTEXTO Proposal".

I do not draw the same conclusions as you based on the latest thread.

What do others think?

    Patrik



On 28 jul 2009, at 16.50, Chris Wright wrote:

> Patrik,
>
> Final follow up from our conversation yesterday, the point we were  
> trying to make about hyphen-minus is as follows:
>
> CONTEXTO for HYPHEN-MINUS
>
> * Is similar to the section in the protocol disallowing consecutive  
> hyphens in the third and fourth position (4.2.3.1 of protocol  
> document)
> * Is applied to Unicode labels; the encoded label does not violate  
> host name syntax
> * Has no context; the surrounding characters do not influence this  
> test
>
> I assume the rationale behind the prohibition of HYPHEN-MINUS at the  
> beginning or end of a label is to carry across host name syntax  
> restrictions into the Unicode label space. This appears to be  
> attempting to achieve similar goals to section 4.2.3.1 in the  
> protocol document by disallowing consecutive hyphens in the third  
> and fourth positions. These two restrictions should appear in the  
> same place.
>
> To clear any confusion that may have arisen during limited  
> discussion last week, the context rule is applied to the putative U- 
> label, therefore the DNS and host name syntax restrictions do not  
> apply (yet). Consider the label b[U+00FC]cher-. The output of this  
> label through the punycode algorithm when appended with the ACE  
> prefix gives gives xn--bcher--3ya. Note this label conforms to the  
> host name syntax.
>
> Thus for consistency, simplicity and clarity sake I propose the  
> following:
>
> In protocol change:
>
> 4.2.3.1. Consecutive Hyphens
> The Unicode string MUST NOT contain "--" (two consecutive hyphens)  
> in the third and fourth character positions.
>
> to
>
> 4.2.3.1. Hyphen Restrictions
> The Unicode string MUST NOT contain "--" (two consecutive hyphens)  
> in the third and fourth character positions and MUST NOT start or  
> end with a "-" (hyphen).
>
> And then remove the context rule from the tables document and return  
> hyphen to PVALID status as with all other LDH characters
>
> Thanks
>
> Chris
>
>

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