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Meaning of scripting feature strings

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Sun, 25 Feb 2007 16:27:21 +0100
To: www-svg@w3.org
Message-Id: <200702251627.21950.Dr.O.Hoffmann@gmx.de>


currently I'm thinking about the meaning of 
Feature String:
User Agent Supports:
Script Module
In SVG 1.1 Appendix O: Feature Strings

or in the CR SVG Tiny 1.2: 

J.1 Specific feature strings

Support for a feature string indicates that the SVG Viewer can process 
and render successfully all of the elements, attributes and language 
features listed in the feature column.
http://www.w3.org/Graphics/SVG/feature/1.2/#Scripting          script

Does this mean, 
a) that requiredFeatures returns "false" if scripting is
   switched off by the user?
b) that requiredFeatures returns "false" if the content-type of 
   scripting specified by the type attribute of the script element
   or in the contentScriptType attribute is unknown?
   If this is the case - has the user agent to analyse just the 
   document fragment related to the switch element or requiredFeatures
   attribute, if the content-type needed in this fragment is
   known, or has the viewer to analyse the complete document?
c) or are these requiredFeatures returns just philosophical statements
   about the general possibilities to support scripting in 
   any way or under some specific conditions with only one or a 
   few scripting languages or with in general with all possible 
   scripting languages?
I think, it is of practical importance for authors to be able to
provide acessible documents even if they include scripting to
be able to switch with this feature to alternate content, if
a) the viewer supports in general 'no-scripting'
b) the scripting is switched off by the user
c) the script languages known by the viewer are different from
   those used by the author
d) the script language version is different from the supported
   versions known by the viewer (maybe it is possible to check
   this inside the script language and then SVG has luckily 
   nothing to do with this)
requiredFeatures or another feature should be able to offer this 
for authors, else it will be impossible for them to use scripting
in any document for accessibility reasons.

I already detected such problems in one viewer and a related 
problem in two viewers, because the feature string  
was not known by the viewer.
Received on Sunday, 25 February 2007 15:28:29 UTC

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