[DFDL-WG] what do we allow in DFDL expressions after "/"

In reexamining the grammar for the DFDL expression language, I have the following question In a path Step/Step/Step[Index] What can Step be? I know it can be ".." or parent::QName or child::QName or just an NCName or QName, Those are all what the XPath grammar calls AxisStep. anything else? The grammar can be changed in a very small way from the original XPath grammar if the above are the only possibilities. the clause StepExpr ::= FilterExpr | AxisStep can just be changed to StepExpr ::= AxisStep -- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com