Re: [Simple] [Technical Errata Reported] RFC5261 (3477)

Bjoern Hoehrmann <derhoermi@gmx.net> Tue, 05 February 2013 11:17 UTC

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From: Bjoern Hoehrmann <derhoermi@gmx.net>
To: RFC Errata System <rfc-editor@rfc-editor.org>
Date: Tue, 05 Feb 2013 12:16:58 +0100
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Cc: dret@berkeley.edu, jari.urpalainen@nokia.com, simple@ietf.org, hisham.khartabil@gmail.com
Subject: Re: [Simple] [Technical Errata Reported] RFC5261 (3477)
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* RFC Errata System wrote:
>Original Text
>-------------
>In XPath 2.0, a "bar" selector
>not only matches an unqualified <bar> element, but also matches a
>qualified <bar> element that is in scope of a default namespace
>declaration.  In contrast, in this specification, a selector without
>a prefix only matches one element, and it may match an element with
>or without a prefix but only if the namespace it's qualified with (or
>none) is an exact match.

>Notes
>-----
>The original text is not easy to understand, but seems to assume that
>an unprefixed name in XPath 2.0 matches both unprefixed names, and 
>prefixed ones that have the same namespace than the default namespace of 
>the XPath static context. This is not the case: Matching depends on how 
>the "default element/type namespace" of the XPath static context is 
>defined, and then matches either namespace-less elements, or those in 
>the "default element/type namespace", but never both. This context, 
>however, is defined by the XPath itself, not by the document. Thus, it 
>can be set externally and could be set to the diff document's default 
>namespace (if there is one). In that case, XPath 2.0 can be used to 
>evaluate XML Patch selectors.

Indeed, see <http://www.w3.org/TR/xpath20/#node-tests>;, 3rd paragraph.

(I do note that this is not the only difference between XPath 1.0 and
XPath 2.0, so the conclusion that then XPath 2.0 can be used to evalu-
ate XML Patch selectors is not necessarily correct, especially if it
cannot be assumed that defaults like "Default element/type namespace"
cannot be assumed to be chosen to maximise compatibility. But that is
out of scope of the Original Text this item is concerned with.)
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
Am Badedeich 7 · Telefon: +49(0)160/4415681 · http://www.bjoernsworld.de
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