validation NEW must evaluation
diff --git a/src/common.h b/src/common.h
index ab4aa13..15467e4 100644
--- a/src/common.h
+++ b/src/common.h
@@ -228,6 +228,7 @@
 #define LY_VCODE_DEV_NOT_PRESENT LYVE_REFERENCE, "Invalid deviation %s \"%s\" property \"%s\" which is not present."
 
 #define LY_VCODE_NOWHEN         LYVE_DATA, "When condition \"%s\" not satisfied."
+#define LY_VCODE_NOMUST         LYVE_DATA, "Must condition \"%s\" not satisfied."
 #define LY_VCODE_NOMAND         LYVE_DATA, "Mandatory node \"%s\" instance does not exist."
 #define LY_VCODE_NOMIN          LYVE_DATA, "Too few \"%s\" instances."
 #define LY_VCODE_NOMAX          LYVE_DATA, "Too many \"%s\" instances."