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Re: interpreting W3C C14N Rec.

• From: ht@markup.co.uk (Henry S. Thompson)
• To: Steve Newcomb <srn@coolheads.com>
• Date: Sun, 25 Oct 2015 22:31:43 +0000

Steve Newcomb <srn@coolheads.com> writes:

> Maybe John Cowan and/or *you*, dear reader, can help me understand the
> following quote from http://www.w3.org/TR/xml-c14n#Example-Chars :

> ----

> *Note:* The last element, |normId|, is well-formed but violates a
> validity constraint for attributes of type ID. For testing canonical
> XML implementations based on validating processors, remove the line
> containing this element from the input and canonical form. In general,
> XML consumers should be discouraged from using this feature of XML.

> ----

> Specifically, I'm wondering what is "this feature" that XML consumers
> should be discouraged from using, and why.

I'll bite.  I think it's that you can get away with invalid values of
ID-declared attributes if you stick with a conservative
well-formed-enforcement only parser.  The doc. is saying it's on
balance a bad idea to take advantage of this.

In part, I presume, because many XML parsers actually fall into the
useful category acknowledged by the spec, i.e. not validating, but do
read the doctype, in which case they _must_ mark the types of
attributes.  This leads to a borderline contradictory situation with,
for example, as simple a case as <a id="3b"/>.

ht
-- 
		    Henry S. Thompson, Markup Systems Ltd.
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• Follow-Ups:
  • Re: Re: interpreting W3C C14N Rec.
    • From: John Cowan <johnwcowan@gmail.com>

• References:
  • interpreting W3C C14N Rec.
    • From: Steve Newcomb <srn@coolheads.com>