Hello, Robert Nagle wrote:

<?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" exclude-result-prefixes="xs" version="2.0"> <xsl:import href="http://docbook.sourceforge.net/release/xsl/1.75.1/epub/docbook.xsl"/> </xsl:stylesheet>

You should write your DocBook customization layer as an XSLT 1.0 stylesheet and validate it with an XSLT 1.0 processor because some validation errors will be always reported for the DocBook stylesheets with an XSLT 2.0 processor.

I have some meta questions with regard to the general process of debugging here.

1. I assume that xslt v2 is better because it's a bigger number (and I've glanced over the differences in syntax, etc). Can you think of a reason why something would fail when version 2 is specified which would not be the case if version 1 is specified? Is best practice just to play it safe and go with version 1, or should I generally use 2 unless otherwise specified?

You should go with the target version of the stylesheet (the 'version' attribute) because sometimes there are important semantic differences (and different evaluation results) between the XSLT 1.0 version and the XSLT 2.0 version of the same expression applied to the same input XML document.

2. I'm guessing that it's easier to debug a local copy of a xsl file than a remote one (in this case version 1.7.5.1 of the epub-xsl transform. which is different from the local version (which is 1.7.4 that came with 10.2). Is there a way that Oxygen knows to associate the URL in the xsl import command with a local file or files on my Windows machine? I don't know how to do this.

Both a local version and a remote one can be used in the XSLT debugger because the debugger reads the content of the stylesheet from the specified URL. You can map the URL of a remote stylesheet to a local version with an XML catalog and in this case the debugger uses the local mapped URL instead of the remote one specified in the stylesheet. The mapping for DocBook stylesheets is already done in the built-in catalog of Oxygen but if there is a new version available you can modify this catalog or add a new one in Preferences -> XML -> XML Catalog. You can read about the XML catalog support in the User Manual: http://www.oxygenxml.com/doc/ug-oxygen/using-XML-Catalogs.html

3. (Now for my really naive question). What's the best way to debug XSLT messages. Should I start at the source xsl of the file(s) being imported here. Or should I be looking up references in Saxon parser or using some Oxygen debugging view. I realize that the answer is probably "it depends", but where does one start first?

Do you mean to debug the XSLT execution error messages as the ones reported above? For the DocBook stylesheets if you use an XSLT 1.0 processor you should get errors only in your customization layer, not in the original stylesheets and such errors are probably caused by using incorrectly an XSLT feature (which means grab an XSLT tutorial!). Do you mean to debug the result of an XSLT transformation that is not the expected one but it is generated without XSLT validation/execution errors? You should start from the unexpected area of the output by clicking on it in the Text output view or the XHTML output view of the XSLT Debugger perspective (the right side of the window in the debugger perspective) that will highlight both the XML element and the XSLT instruction that generated exactly that output area. See the output views of the debugger: http://www.oxygenxml.com/doc/ug-oxygen/determining-what-template-generated-p...

Thanks.

Robert

Regards, Sorin