ADDED   mttroot/mtt/lib/cr/hh/causality.hh
Index: mttroot/mtt/lib/cr/hh/causality.hh
==================================================================
--- /dev/null
+++ mttroot/mtt/lib/cr/hh/causality.hh
@@ -0,0 +1,8 @@
+#ifndef CAUSALITY_HH
+#define CAUSALITY_HH
+
+enum causality { effort, flow, state };
+
+typedef enum causality causality_t;
+
+#endif