Dear Radu, thanks very much for your most helpful explanations. Although I knew about the idea of xslthl-saxonhe-extension-function.jar and I missed to check the CLASSPATH definition which is a beginner's fault (sorry), yet after understanding the background (saxon...) this gives me a better underst...

As I do have my own (very powerful) additional Xpower-plugin implemented, I am using the command line. You might remember me from a DITA-OT conference in Munich years ago, where I gave a short presentation of the xpower-plugin and I remember your question to look-up my mechanism in order to get high...

I confirm that the language-xml hightlighting does not work - for me since version 3.4.1 and later. To be precise, I'm not after having that highlight in the oxygen-GUI but in the result of the DITA-OT process (PDF). In ...\Dita-OT3\plugins\com.oxygenxml.highlight\common.xsl the code <xsl:template n...