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Question about forward and backward compatibility

From: Robert O'Callahan <rocallahan@gmail.com>
Date: Tue, 7 Dec 2004 12:15:16 -0500
Message-ID: <11e3066004120709151d7e81a4@mail.gmail.com>
To: www-svg@w3.org

I'm trying to understand how authors write SVG content that will be
compatible across different SVG versions and user agents.

1) Is there a way for authors to write a single SVG file that will
take advantage of SVG 1.2 features but degrade gracefully in a user
agent supporting only 1.1? It appears not, since the 1.1 user agent is
required to visually show error due to the presence of 1.2-specific
elements and attributes. Or is the WG taking the position that 1.2
extends 1.1 such that 1.2 elements and attributes are being
retroactively added to the 1.1 DTD?
http://www.w3.org/TR/SVG/implnote.html#ErrorProcessing

2) Given the presence of 'switch' and feature strings, are user agents
allowed to implement any SVG 1.1 subset that is exactly the union of a
set of feature modules? Or is this now officially deprecated by SVG
1.2 WD section 2?
http://www.w3.org/TR/SVG/feature.html
http://www.w3.org/TR/SVG12/profiling.html

3) It has been useful in our work on CSS to prototype our
implementation of new CSS features by making the properties first
available with a -moz prefix, and then once our implementation is
solid enough (which depends partly on people experimenting with our
releases), we make the properties available with the standard names
too. It's not clear to do something similar with SVG. One option is to
initially enable our SVG prototype only via a Mozilla-specific
nonstandard MIME type, which lets Mozilla-specific application authors
and experimenters play with it, and later (mid 2005 for SVG Basic?)
enable it under the real MIME type and for mixed documents, once we're
satisfied that it meets correctness, performance and W3C profiling
requirements. We're looking for feedback on this.
Received on Thursday, 9 December 2004 00:08:44 GMT

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