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Re: [css-style-attr] SVG WG comments on CSS Styling Attributes Level 1

From: Chris Lilley <chris@w3.org>
Date: Wed, 25 Aug 2010 00:06:08 +0200
Message-ID: <1057941668.20100825000608@w3.org>
To: "Anne van Kesteren" <annevk@opera.com>
CC: fantasai <fantasai.lists@inkedblade.net>, "Alex Danilo" <alex@abbra.com>, <www-style@w3.org>, www-svg <www-svg@w3.org>
On Tuesday, August 24, 2010, 3:08:18 PM, Anne wrote:

AvK> On Tue, 24 Aug 2010 14:57:14 +0200, Alex Danilo <alex@abbra.com> wrote:
>>> This issue is out of scope for the Styling Attributes specification.

>>> (Also, the CSSWG has already resolved not to make this change.)

>> Could I perhaps ask why?

>> Looking back in time by reading the source code of Unix
>> edition 7 which dates back _a long time_ (the '70s) I see that the
>> 'C' function 'scanf' can handle parsing scientific notation.

Indeed, lex allows scientific notation (as the original comment from SVG notes). CSS however uses a modified lex grammar which does not allow scientific notation.

CSS has two grammars, one specific to the 'level' of CSS (1, 2, 3 ..) and one which is core or generic, and applies to all of CSS. It is the core grammar that disallows scientific notation.

AvK> (The group is somewhat split on whether we should add scientific notation,
AvK> but most implementors are in favor (some already support it), so it will
AvK> very likely happen in due course.)

It was interesting to hear during todays discussion that not only does Firefox already support scientific notation for SVG properties in stylesheets, as previously noted, but IE9 preview supports it also.

As Hakon is sometimes fond of saying, 'the implementations are going to do it anyway' although I don't agree with his conclusion in that case that 'maybe it doesn't need to be in the spec but  people will do it'. This also seems to be Anne's point.

Tab Atkins argued in favour, and Daniel Glazman pointed out that everyone who has a need of scientific notation understands it - its on calculators and computers, schoolchildren use it -  but Bert Bos and Håkon Lie blocked any change, Bert appealing to 'no-one wants it' and the inviolacy of the core grammar and Håkon appealing to 'no one understands it', suggesting units with multipliers instead (font-size: 12 angstroms, as if that would help or was what we wanted) and, while opposing adding it, also insisting that if added, it use a different syntax with Unicode values for the exponents (he hates the standard scientific notation used on computers for the last 40 years, it seems). Interoperability of the twenty or so SVG implementations over the years (which allow scientific notation in attribute values but are barred by CSS rules from allowing the same thing in stylesheets) was simply ignored or treated as irrrelevant. Because HTML doesn't use it, therefore no-one wants it.  

The end result of the lengthy, unfriendly and divisive discussion was not only that the proposal failed to get scientific notation allowed (as I predicted, in SVG WG discussions, it would) but that also a number of people took the opportunity to deride SVG in general, to posit strawman outlandish examples that they could demolish, to declaim "I don't understand!" and so forth. A big change from the generally positive, lets-make-this-work attitude that has characterized CSS-SVG discourse, for example on the FX task force, in recent years.

 Chris Lilley   Technical Director, Interaction Domain                 
 W3C Graphics Activity Lead, Fonts Activity Lead
 Co-Chair, W3C Hypertext CG
 Member, CSS, WebFonts, SVG Working Groups
Received on Wednesday, 25 August 2010 08:25:55 UTC

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