Re: Issue 194: restricting allowed characters in quoted-pair

Henrik Nordstrom wrote:
> ons 2009-09-16 klockan 16:34 +1000 skrev Mark Nottingham:
>> So, strict BNF with a note in prose that old implementations may quote  
>> other characters? Works for me.
> 
> Usually this kind of things is done the other way around. Open BNF with
> restrictions in prose on what may be produced. Or if one wants to go the
> long way by introducing "obsolete/old" BNF constructs for stuff which is
> should not be produced but still accepted by parsers for legacy reasons.
> 
> Notes in prose should not require parsers to go outside the BNF.

OK, for now I have only made the change disallowing non-HTAB control 
characters in quoted-pair 
(<http://trac.tools.ietf.org/wg/httpbis/trac/changeset/696>).

I have not yet added any prose about recommending not to use quotes when 
not needed. With respect to that, we need to decide:

- whether that's purely advisory or a requirement (SHOULD?), I lean to 
the former, and

- where exactly to state it, as quoted-pair is used both inside 
quoted-string and comment, and the characters that need escaping thus 
differ; one way to fix this would be to change the ABNF so "comment" 
gets it's own quoted-cpair rule.

BR, Julian