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Re: XLink 1.1: "URI reference" "checking"

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Wed, 25 Jan 2006 21:09:09 +0100
To: ht@inf.ed.ac.uk (Henry S. Thompson)
Cc: www-xml-linking-comments@w3.org
Message-ID: <ljkft1t4k57k8gnr6c7t5enhmn5gg4g69n@hive.bjoern.hoehrmann.de>

* Henry S. Thompson wrote:
>> I don't understand, first you say it's impractical for any application
>> to check for syntax errors, then you say it's probably not impractical
>> but you don't require it anyway and now you say of course, in the end,
>> implementations should check for syntax errors.
>
>Sorry, the last clause is _not_ what I said.  I think it's entirely
>reasonable to distinguish between implementations of XLink itself, and
>the libraries it uses to access implementations of _other_ specs and
>RFCs which it depends on.  We do _not_ require the XLink
>implementation itself to enforce 3986 syntax constraints.  It's not
>necessary or appropriate for the XLink spec. to say "Of course, all
>libraries you use should be conformant implementations of whatever it
>is that they implement".  It's a question of subsidiarity, to use a
>phrase popular in Europe not long ago.

A web agent that implements XLink 1.1 is a black box, it either recovers
silently from syntax errors in what should be a URI reference or it does
not. The text is

  Because it is impractical for any application to check that a value
  is a URI reference, this specification follows the lead of [IETF RFC
  3986] in this matter and imposes no such conformance testing
  requirement on XLink applications.

This specifically allows XLink 1.1 implementations to silently recover
from errors. If there is, as you seem to imply, any specification that
says that's a bad idea, then you've taken extra steps to override these
specifications. Indeed, if you remove this text it would seem clear that
XLink 1.1 implementations must not apply XLink semantics to elements
that have XLink attributes that have such syntax errors, considering the
proposed changes to what it means to perform markup conformance testing.
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
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Received on Wednesday, 25 January 2006 20:08:44 GMT

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