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

On Fri, Sep 25, 2009 at 1:40 PM, Julian Reschke <julian.reschke@gmx.de>wrote:

> 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.
>

I would say implementations SHOULD NOT use quotes where not required but
MUST always accept them.

Sam