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Xinclude processing

1. XInclude in docbook
2. XInclude produces parser errors?

1.

XInclude in docbook

DaveP



Don't forget Bob Staytons site. DaveP

2.

XInclude produces parser errors?

Daniel Veillard


> When compiling my modular docbook file I get this xmllint error message.
> What am I doing wrong?

Nothing. It's a problem between DocBook DTD and XInclude.

> $ xmllint --xinclude --postvalid IDS5webUGbook.xml > out.xml
> IDS5web/1_Introduction/chapter_all_introduction.xml:3: No declaration for
> attribute base of element chapter .

Since there seems to be some confusion about the exact problem let me explain a bit what's going on:

xmllint --xinclude --postvalid does the following:

1/ parse the document, load the DTD but does not validate while parsing
2/ apply the XInclude processing which will recursively traverse the document(s) and include the new informations gathered from new documents (or text source)
3/ validate the resulting in-memory tree with the DTD from the "main" document.

So now what's this base attribute, where does it come from, and why:

1/ it's actually xml:base , an attribute which allows to set the base for URI-Reference computation done in the subtree of the document.
2/ it is added by XInclude processing to not break references done from included document. Say that main.xml includes subdir/chapter.xml and that subdir/chapter.xml references an image img.png . The rules for references expects the image to be found in subdir/img.png
3/ XInclude has no notion of what in teh included document might be a reference. So to preserve the linking functionality it mandates to add an xml:base="subdir/chapter.xml" at the point where the inclusion occured si that the reference from the resulting document to the image be preserved.

The consequence is:

- there is nothing to prevent this from an authoring point of view except keeping all the included fragment in the same directory as the main document

- the only solution is to get Docbook XML DTD to allow xml:base as a #IMPLIED attributes on the elements which are likely to be top of inserted documents. I though this was agreed upon but didn't checked the progress, Norm or Paul can probably tell us more about this.

At the moment you can safely ignore any [xml:]base attribute error message resulting from postvalid after XInclude processing.

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