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

["Kent Karlsson" <kentk@md.chalmers.se>]

> 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.

If that long sequence were displayable properly (it's a bit long for that), the
accents would stack up on top of each other, not be displayed as you indicate.

> 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.

I think that would be a good idea for the subnames* (otherwise the 
combining character applies to something before the name, or to
a period in the name). Ideally, a hyphen-minus should also never
be followed by a combining character in a domain/host** name.

However, no technical restriction to at least two characters in a
domain/host name should be accepted.

        Kind regards
        /kent k

* subnames (here): the name parts that are delimited by full stops.

** I will not try to keep track of which is what.  That issue appears totally confused.