diff --git a/src/main/antlr/cosmas/c2ps_opPROX.g b/src/main/antlr/cosmas/c2ps_opPROX.g
index 5d1ba5a..bb1fb18 100644
--- a/src/main/antlr/cosmas/c2ps_opPROX.g
+++ b/src/main/antlr/cosmas/c2ps_opPROX.g
@@ -75,7 +75,7 @@
 		->				       ^(RANGE VAL0 $m1);
 
 proxMeasure
-	:	(m='w'|m='s'|m='p'|m='t') -> ^(MEAS $m);
+	:	(meas='w'|meas='s'|meas='p'|meas='t') -> {c2ps_opPROX.checkMeasure($meas)} ;  // {c2ps_opPROX.checkMeasure($meas)} ? ^(MEAS $meas);
 
 proxDistMin
 	:	DISTVALUE;
diff --git a/src/main/java/de/ids_mannheim/korap/query/parse/cosmas/c2ps_opPROX.java b/src/main/java/de/ids_mannheim/korap/query/parse/cosmas/c2ps_opPROX.java
index 66daf0d..6458dd3 100644
--- a/src/main/java/de/ids_mannheim/korap/query/parse/cosmas/c2ps_opPROX.java
+++ b/src/main/java/de/ids_mannheim/korap/query/parse/cosmas/c2ps_opPROX.java
@@ -88,7 +88,13 @@
         return tree;
     }
 
-
+	public static boolean checkMeasure( Object measure)
+	{
+		System.err.printf("Debug: checkMeasure: measure = %s.\n",
+				measure == null ? "null" : "not null");
+		return true;
+	}
+	
     /*
      * main testprogram:
      */