Review of XForms 2.0 section 11

All,
 
At 11.17, a global Javascript variable named "XForms" is introduced:
* why not mention it already at 10.8?
* it would be much more convenient for an engine such as XSLTForms to specify
methods instead of properties: ".getVar(name)" instead of ".var.name",
"getContext()" instead of ".context". If not, each and every possible variable
has to be stored in XForms.var before executing the script action, whether it
will be effectively used or not.
* is a script action allowed to modify an XForms variable?
* which mapping should be used for sequences? Javascript arrays?
--Alain