If you are extending the grammar of the Scenarios module for use with Commerce scenario elements, you can make use of some additional specialized tags.
The header for a grammar extension definition file that includes Commerce scenario elements looks like this:
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <?xcl-stylesheet resource="atg/ui/commerce/scenario/commerce-grammar.xsl"?> <?xcl-stylesheet resource="atg/ui/scenario/expression/scenario-grammar.xsl"?> <?xcl-stylesheet resource="atg/ui/expreditor/xcl/grammar.xsl"?>