Returns a full list of the names and values of variables currently referenced.
Returns an XML document in the "Processing:Command" namespace with a <pc:Variables> document node and, for each variable, a <pc:Variable> element with a name attribute that contains the name of the variable, and with the following content:
•For a string variable, a text node representing the current value of the variable.
•For a node set variable, a literal XML fragment representing the current value of the variable.
•For a queue variable, a list of <Queue> elements containing queued variable values, in the document order in which the values were enqueued.
An example result value is: