The <oXygen/> XSLT/XQuery Debugger allows you to interrupt XSLT/XQuery processing to gather information about variables and processor execution at particular points.
To insert a breakpoint:
In the XML source document or the XSLT/XQuery document that you want to set a breakpoint, place your cursor on the line where you want the breakpoint to be. You can set breakpoints on XML source only for XSLT debugging sessions.
Select
-> -> or directly click with the mouse the left side stripe of the editor window on the line where you want the breakpoint to be.