Okay, I now have a pretty good setup for doing validation of RNG with embedded Schematron inside the oXygen 4.0 environment. Here's what I did, see if you like my system:
(1) Create a folder ../oXygen4.0/Schematron.
(2) Into that folder, put the following files (see below for sources): RNG2Schtrn.xsl, skeleton1-5.xsl, schematron-basic.xsl. (You can get Eddie Robertsson's RNG2Schtrn.xsl from the topologi site, in the Schema Validator freeware download. The other two files are part of the Schematron package you can get from
http://xml.ascc.net/schematron/1.5/. If you want to use the schematron 1.6 beta, you can get that from topologi's site. In that case use skeleton1-6.xsl plus ISOprepro.xsl; change the <include> in schematron-basic.xsl to reference skeleton1-6 instead of 1-5.)
(3) Create a transformation scenario for .rng files named "Compile RNG-embedded Schematron", as follows: XSL URL=RNG2Schtrn.xsl; cascade stylesheet(1) is schematron-basic.xsl. (If you are using 1.6, then cascade stylesheet(1) is ISOprepro.xsl and cascade stylesheet(2) is the as-modified schematron-basic.xsl.) As the output, specify Save as = ${cfd}\${cfn}.sch
(4) Create a transformation scenario for .xml files named "Validate against Schematron", as follows: XSL URL=${cfd}\${cfn}.sch. For output, specify Save as=${cfd}\SchematronResult.txt
(5) Make sure your .rng with embedded schematron constraints uses the embedding syntax suggested by Eddie Robertsson in his recent xml.com article (
http://www.xml.com/pub/a/2004/02/11/relaxtron.html)
(6) Put you rng schema with embedded schematron in the same folder as your instance documents to be validated.
(7) When you have the schema the way you like it, run the "Compile RNG-embedded Schematron" transformation scenario on it.
(8) Open your instance document in the editor. Do the structure validation in the usual way by selecting "Validate document".
(9) If the structure validation is okay, apply the schematron validation by invoking the transformation scenario "Valdiate against schematron". Result messages will be shown in the result pane below the editor pane, and will also be saved to the text file SchematronResult.txt in the same folder as the instance.
Try it, see if it works for you, and have fun. Let me know if problems.
John