Glossary

I am cleaning up the glossary.
https://www.w3.org/community/xformsusers/wiki/XForms_2.0#Glossary_Of_Terms

* There was no definition of 'atomic value'. Doing a search I couldn't  
quickly find a decent reference or definition (W3C Schools: a value  
without children or parent; Schema part 2: Atomic datatypes are those  
having values which are regarded by this specification as being  
indivisible.) I've left it [TBD] at the moment, but am happy to receive  
suggestions for good wording.

* Instance data node is defined in terms of XPath 1.0. There surely must  
be a more general definition.

Actually, references to various versions of XPath are sprinkled around the  
spec; they need to be cleaned up too. I'll devote a separate email to that.

Steven