W3C home > Mailing lists > Public > public-media-fragment@w3.org > February 2010

Re: ABNF or code fragments?

From: Philip Jägenstedt <philipj@opera.com>
Date: Wed, 24 Feb 2010 18:45:10 +0800
To: "Jack Jansen" <Jack.Jansen@cwi.nl>
Cc: "Yves Lafon" <ylafon@w3.org>, "Media Fragment" <public-media-fragment@w3.org>
Message-ID: <op.u8mn5kxlatwj1d@philip-pc.oslo.opera.com>
On Wed, 24 Feb 2010 18:16:38 +0800, Jack Jansen <Jack.Jansen@cwi.nl> wrote:

> On 24 feb 2010, at 10:35, Philip Jägenstedt wrote:
>> We can decide for ourselves what is valid. I think it should be invalid  
>> to use percent encoding where it isn't needed, so that validators will  
>> warn against using #%74=1 and other stupid things. (But it would still  
>> work in conforming implementations.)
> Huh?
> Either it is valid (which seems to imply that percent-escape-processing  
> happens early) or it is not (if percent-processing happens late). If it  
> is valid then a validator has no business warning about it. This would  
> be a completely different case from, say, t=10,8, for which a validator  
> could conceivably warn that it is syntactically valid, but probably  
> semantically incorrect.

Only syntax that we actually want authors to use should be valid, but the  
processing rules need to tolerate some invalid syntax. For example,  
#t=1&fruit=bananas ought to be invalid, but implementations must ignore it  
(names/values it doesn't recognize) because otherwise it's impossible to  
extend MF in the future without breaking all existing implementations.

About percent encoding, I think the current processing is what it should  
be, which is close to what web servers currently do with query strings. We  
can make any strange percent-encoding valid to match processing, but I  
don't see why we would want to, as it is likely an authoring error and  
they would appreciate being told as much by validators.

Philip Jägenstedt
Core Developer
Opera Software
Received on Wednesday, 24 February 2010 10:45:58 UTC

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