--- a/absyntax/absyntax.def	Tue Jul 29 13:39:40 2014 +0100
+++ b/absyntax/absyntax.def	Thu Jul 31 17:49:44 2014 +0100
@@ -130,6 +130,11 @@
 /*********************/
 /* B 1.2 - Constants */
 /*********************/
+/*********************************/
+/* B 1.2.XX - Reference Literals */
+/*********************************/
+/* defined in IEC 61131-3 v3 - Basically the 'NULL' keyword! */
+SYM_REF0(ref_value_null_literal_c)
 
 /******************************/
 /* B 1.2.1 - Numeric Literals */