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SVG12: Error Processing

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Sat, 15 Jan 2005 22:20:40 +0100
To: www-svg@w3.org
Message-ID: <41ed79b6.266453984@smtp.bjoern.hoehrmann.de>

Dear Scalable Vector Graphics Working Group,

  http://www.w3.org/TR/2004/WD-SVG12-20041027/ does not seem to define
error processing in a number of cases, specifically for elements that
lack a required attribute, elements that lack mandatory content such as
sub-elements, elements that have illegal content such as an element in
the SVG namespace (e.g., a svg:script element inside an svg:script
element), and many other situations like documents that include the xml-
stylesheet processing instruction in place where it must not appear or
if it does not meet the syntax requirements of the Recommendation like
<?xml-stylesheet href="x" type="text/css" title="&#x20FFFF;"?>.

Other parts of the error processing requirements need clarification,
e.g. a SVG document fragment is said to be "in error" "When the content
does not conform to the XML 1.0 specification [XML10], such as the use
of incorrect XML syntax"; it is for example not clear whether such con-
formance involves only well-formedness or whether a document that is in-
valid or has other errors as defined in XML 1.0 is in error aswell. It
is further not clear whether this means that all XML 1.1 documents would
be "in error".

For "When an element has an attribute or property value which is not
permissible according to this specification" it is not clear whether
this is meant to include attributes in no namespace on elements in the
SVG namespace that are not permissible on the element (e.g., <svg:a
foo="bar" ...>).

For "The document shall be rendered up to, but not including, the first
element which has an error" it is not clear how to satisfy the require-
ment if the document is in error due to errors before reading the root
element or if the root element is in error as in those cases, the model
would not allow any rendering as far as I can see.

In "animations shall stop at the point at which an error is encountered"
it is not clear what happens with animation elements that did not begin
yet and whether it would be considered a restart of the animation if the
document goes out of the "in error" state. Maybe animations should pause
rather than "stop" or end...

For "In particular, error processing shall be disabled whenever redraw
has been suspended via DOM calls to suspendRedraw()" it is not clear
whether calling forceRedraw() while redraw has been suspended triggers
error processing.

Please change the draft such that this is well-defined; if there will be
cases left where error processing is not defined, please add a note that
states this clearly.

Please add a note that animation elements can cause the document to be
in error before the animation begins, e.g. for

  ...
  <text ...>
    <animate attributeName = 'textLength' values = '0;1;2;-1'  ... />
  ...

unless the values attribute gets changed, the document never begins. An
example where an animation can cause a document to be in error would be
useful.

regards.
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
Weinh. Str. 22 · Telefon: +49(0)621/4309674 · http://www.bjoernsworld.de
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Received on Saturday, 15 January 2005 21:20:35 GMT

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