diff --git a/src/main/java/org/gcube/dataanalysis/geo/wps/mappings/WPS2SM.java b/src/main/java/org/gcube/dataanalysis/geo/wps/mappings/WPS2SM.java
index 25eb1c8..f29184f 100644
--- a/src/main/java/org/gcube/dataanalysis/geo/wps/mappings/WPS2SM.java
+++ b/src/main/java/org/gcube/dataanalysis/geo/wps/mappings/WPS2SM.java
@@ -38,14 +38,18 @@ public class WPS2SM {
 		AnalysisLogger.getLogger().debug("WPS type:" + type.getStringValue());
 		String guessedType = guessWPSLiteralType(type);
 		AnalysisLogger.getLogger().debug("Guessed type: " + guessedType);
+		
 		// rebuild Abstract
-		if ((defaultValue==null || defaultValue.trim().length()==0) && (guessedType.equals(String.class.getName())))
-			defaultValue=" ";
+		if ((defaultValue==null || defaultValue.trim().length()==0))
+			defaultValue=guessDefaultValue(guessedType);
+		
+		AnalysisLogger.getLogger().debug("Guessed default value: " + defaultValue);
+		
 		Abstract = buildParameterDescription(Abstract, null, uoms, minOcc, maxOcc, defaultValue);
 		if ((maxOcc == 1)||(maxOcc<0)||(maxOcc == 0))
-			converted = new PrimitiveType(guessedType, null, PrimitiveTypes.STRING, title, Abstract, defaultValue,true);
+			converted = new PrimitiveType(guessedType, null, guessPrimitiveType(guessedType), title, Abstract, defaultValue,true);
 		else
-			converted = new PrimitiveTypesList(guessedType, PrimitiveTypes.STRING, title, Abstract, true);
+			converted = new PrimitiveTypesList(String.class.getName(), PrimitiveTypes.STRING, title, Abstract, true);
 		return converted;
 	}
 
@@ -198,6 +202,18 @@ public class WPS2SM {
 		return String.class.getName();
 	}
 
+	public static String guessDefaultValue(String type) {
+		if (type.equals(String.class.getName()))
+			return " ";
+		else
+			return "0";
+	}
 	
+	public static PrimitiveTypes guessPrimitiveType(String type) {
+		if (type.equals(String.class.getName()))
+			return PrimitiveTypes.STRING;
+		else
+			return PrimitiveTypes.NUMBER;
+	}
 	
 }