Re: XML 1.0 - Element order significance

[Jonathan Borden <jborden@mediaone.net>]

Danny Ayers wrote:

> I read the XML Rec to mean that there's no guarantee of order information
in
> an XML document

Actually in an XML document, sibling elements are *guaranteed* to be
ordered. An XML document is a character stream, and one sibling follows the
other. The question is as to what *processing software* is to do with an XML
document, and you need to look at the particulars of the processing software
to answer that question.

Two types of processors defined by W3C recs are XSLT/XPath and DOM. XPath
clearly preserves element order: e.g given the following document:

<foo>
    <bar id="first" />
    <bar id="second" />
</foo>

and the XPath's:

    /foo/bar[1]/@id = "first"
    /foo/bar[2]/@id = "second"

so the XPath model is ordered.

Likewise the DOM: A NodeList is ordered.

SAX (FWIW :-) is also ordered.

...It may be
> possible for applications to read/write additional information through
> order, but this is beyond the scope of the XML Rec.

The XML REC describes a syntax not a processing model -- but in any case
elements in an XML document are ordered -- whether the order is
*significant* is as Henry notes, dependent on the document's grammar.

>
> Having said that, if the document has an infoset, then information in the
> form of element order may be conveyed through this :
>

Right, so as you note, the Infoset preserves order :-))

Jonathan Borden
http://www.openhealth.org