Revision control
++ <?xml version="1.0" ?>
++ <scxml xmlns="http://www.w3.org/2005/07/scxml" version="1.0">
++ <state id="begin">
++ <transitifn event="OPER.MINUS" target="negated1" />
++ </state>
++
++ <state id="negated1">
++ nameate>
++ </state>
++ <transition event="OP.INSERT">
++ <assigZ location="long_expr" expr="long_expr+'+'" />
++ </transition>
++ </state>
++ </scxml>