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Re: [SVG1.1F2 LC] precise data type definition of something like "<coordinate>+"

From: Chris Lilley <chris@w3.org>
Date: Mon, 29 Nov 2010 18:44:30 +0100
Message-ID: <1065600192.20101129184430@w3.org>
To: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>
CC: www-svg@w3.org
On Tuesday, June 29, 2010, 10:29:02 AM, Dr. wrote:

DOH> Hello www-svg,

DOH> I think, it would be interesting to know the precise definition of
DOH> a data type like "<coordinate>+" (and similar constructs for example 
DOH> mentioned in the text chapter).

DOH> Of cource, <coordinate>, <length>, <number> etc are already defined, but still
DOH> I did not find the meaning of '+'.
DOH> What does this exactly mean? Obviously a list as mentioned in the prose
DOH> defintions of the attributes, but it has not the syntax of <list-of-Ts>
DOH> clearly defined in the data type chapter.

DOH> I think, in SVG tiny 1.2 this is typically changed to <list-of-Ts>.

Yes, and we agree this is clearer than the underdefined <foo>+ to which you refer.

DOH> However, this has consequences for animation.
DOH> Something like <coordinate>, <length>, <number> can have an
DOH> additive animation (including to- and by-animation),  <list-of-Ts> not.

Agreed. 

DOH> Following SVG tiny 1.2, this means especially, that it is not possible
DOH> anymore in SVG 1.1 as well to have a to- or by-animation for such 
DOH> text (tspan) attributes like x, y, dx, dy.

It is not clear that it was permitted before. SVG 1.1 First Edition also says <coordinate>+, for example, and this is not the same as <coordinate>.

DOH> This can be a restriction only helpful for tiny 1.2 devices or it can be some
DOH> general idea of simplication - what applies?

The latter.

DOH> My interpretation of  "<coordinate>+" is, that those attributes can be
DOH> additive for each single list item, therefore especially to- or by-animations
DOH> are applicable. 
DOH> However, because I could not find any precise description of '+', there are
DOH> maybe other interpretations as well with the result of different
DOH> implementations (when I was a member of the group I provided already
DOH> some samples including results from different viewers...
DOH> of course the results from implementations are influenced by inconsistencies
DOH> and bugs as well, therefore there is no interpretation identificable, all
DOH> implementations agree on).

We decided to adopt the same approach as SVGT1.2, so <foo>+ has been replaced by <list-of-foo> throughout.

In addition, we added the useful clarifications of section "Paced animation and complex types" from SVGT1.2 to SVG 1.1 Second Edition.

Since the changes adopted in SVGT1.2 were largely motivated by your earlier comments, we hope that the consistency afforded by adopting the same wording in SVG 1.1 Second Edition resolves your comment.

ISSUE-2341 ACTION-2818

-- 
 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 Monday, 29 November 2010 17:44:48 GMT

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