XML Session serializer - XMLDBX

Well, last week or so I noticed that Squirrelmail's session array contained recursive variable references and caused my serializer to crash on infinite recursion. Oh well, that's life. I found the time to add a variable stack for encoding to XML. If a variable is "is_ref" or has a "refcount" greater than 1, the variable stack is searched for a previous occurrence. If the variable has not been seen previously, it is push onto the stack. If it has, only a reference ID of the previous variable is saved in the xml stream. is_ref and refcount are now added as attributes in the XML stream. Anyone want to lend a hand and test the serializer?