RE: Patterns usage in XSLT template rules

> Sorry for not being clear enough, but I had meant to ask "why are
> patterns like (foo) or (/child::foo) considered invalid patterns as
> per XSLT specification ?"

The syntax for patterns was designed as a subset of XPath path expressions
that makes it easy and efficient to test whether a particular node is
selected by the expression or not. Clearly there are a number of ways this
subset could have been expanded - including some useful ways such as
allowing a/b/(d|e) - but on the whole, the current definition seems to have
provided most of what users need while remaining efficient to implement, and
there has been little pressure to change it.

Michael Kay
http://www.saxonica.com/