Using Saxon 9 as a Schematron 1.5 back end

Validator.nu uses a patched version of oNVDL with Xalan as its  
Schematron 1.5 back end. I switched from Saxon 6 to Xalan in order to  
get column numbers in addition to line numbers on errors. However, I'm  
not happy with the performance of Xalan, which is why I'm considering  
going back to Saxon. To do that without feature loss, I need to patch  
Saxon to support column numbers.

Should I put my effort into patching Saxon 6 or 9? That is, can I use  
Saxon 9 without breaking the semantics of Schematron 1.5 schemas that  
use XPath 1.0 queries?

-- 
Henri Sivonen

http://hsivonen.iki.fi/