The relase notes for XXE 10.4 refers to language fixup in XInclude 1.1.
I must first start be exolaining why we should not give too much heed to
what XInclude 1.0 or 1.1 says about language properties.
XInclude need an update. XInclude 1.1 is a Working Groupn Note from
2016 [1], while the final version of a Recommended spec, XInclude 1.0,
is from 2006 [2].
The Note from 2016 includes some innovations such as set-xml-id (though
it should probably also have had a set-id attribute as well). But at the
same time, when it comes to language properties, the spec that it
references, IETF RFC 3066, published in 2001, was outdated when the Note
was published: The current best practise for language tagging, was
specified in 2009 - seven years before the Note was finished [3].
The work on HTML5 begun around 2006, when the first XInclude was
published. In HTML4, the lang attribute behaved different from the
xml:lang attribute. But in HTML5, which implements BCP 47, the
specification of lang has been 'updated' so that lang and xml:lang work
the same (the only difference being that xml:lang only works when
consumed as XML).
So the Working Group Note from 2016 does not pick up all the changes
that happened to HTML and language tagging since 2006. Perhaps that is
the reason why XInclude only talks about xml:lang and not about lang?
XInclude seems to have been created in the spirit of XHTML 1.0, when the
attitude was that we will soon kill text/html. And so, for example,
XInclude 1.1’s section on Language Fixup from 2016, is identical with
XInclude 1.0’s section on Language Fixup from 2006.
Instead, we have ended up with situation where we try to keep HTML as
XML and HTML as text/html as much as possible in sync. In sync, but
different.
It does therefore not make sense anymore that XInclude only considers
xml:lang and ignore lang.
XMLmind XML Editor version 10.,4 is an exmple of this. Per the relase
notes [4], XXE 10.4 “Made the language fixup of the XInclude 1.1
implementation more conforming to the specification.“. (As I mentioned
above, the language fixup of XInclude 1.1 [5] is identical with the
language fixup of XInclude 1.0 [6], so - sorry to say it, but - the
reference to XInclude 1.1 here, simply gives appearans of being an up to
date reference.)
So what is the change in 'language fixup' that has been added in XXE
10.4? Here is an example:
When working with XInclude, it turns out that XXE ignores @lang - only
xml:lang is respected and counted. The consequence being that if, via
XInclude, you embed into another element the following element,
<section lang="en" id="sect01" />
then the way XXE implements 'language fixup' causes the above element to
be embedded as if the language property is unknown, which (as of XXE
10.4) means that XXE adds xml:lang="" to the embedded element:
<section xml:lang="" id="sect01" />
And, if it does not delete the lang attribute, we even get this:
<section xml:lang="" lang="en" id="sect01" />
(Sometimes the @lang is deleted, other times it is not, I am not yet
certain about when what happens - but both things are meaningless.)
Which means that XXE 10.4’s implementation of XInclude has created a
document which is invalid, since, when both xml:lang and lang are used,
they must be in agreement. Also, it has failed to take the lang="en"
attribute into account, thus loosing information. Further more, if the
end result - the resulting document of the xinclusion - is meant for
consumption by text/HTML consumers, then text/HTML consumers do not
understand the xml:lang attribute etc.
Solution: The solution is to treat @lang and xml:lang equally. Thus in
the example above, the result would have become this:
<section lang="en" id="sect01" />
Or (if you want to consider that not all Xinclude processors - if anyone
at all - handle the lang attribnuite) this:
<section lang="en" xml:lang="en" id="sect01" />
[1] https://www.w3.org/TR/xinclude-11/
[2] https://www.w3.org/TR/xinclude/
[3] https://www.ietf.org/rfc/bcp/bcp47.txt
[4] https://xmlmind.com/xmleditor/changes.html#v10.4.0
[5] https://www.w3.org/TR/xinclude-11/#language
[6] https://www.w3.org/TR/xinclude/#language
Leif Halvard Silli
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