Revision control
++ <?xml version="1.0" encoding="UTF-8"?>
++ <scxml name="DataInNullDataModel" xmlns="http://www.w3.org/2005/07/scxml" version="1.0" initial="a">
++ <datamodel>
++ <data id="x" expr="2"/>
++ </datamodel>
++ <state id="a"></state>
++ </scxml>