RE: How to do an 'existence' test in XSL?

> So there is the problem... how on earth do I process the xml 
> such that it results in an output per +type+ rather than for 
> each instance (is that explained well enough?)... 

The problem is known as grouping. It's not easy in XSLT 1.0, but solutions
are well-known and are explained at
http://www.jenitennison.com/xslt/grouping. For XSLT 2.0 it's much easier, as
there is an <xsl:for-each-group> instruction for the purpose.

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