diff --git a/lib/mess/tree/definition.js b/lib/mess/tree/definition.js
index fc74cfa..c77d2c9 100644
--- a/lib/mess/tree/definition.js
+++ b/lib/mess/tree/definition.js
@@ -21,9 +21,14 @@ tree.Definition.prototype.filter_symbolizer = function(symbolizer) {
 };
 
 tree.Definition.prototype.symbolizers = function() {
-    return this.rules.map(function(rule) {
-        return rule.symbolizer;
-    });
+    // reduce used to make the result of this 
+    // an array of unique values.
+    return this.rules.reduce(function(memo, rule) {
+        if (memo.indexOf(rule.symbolizer) == -1) {
+            memo.push(rule.symbolizer);
+        }
+        return memo;
+    }, []);
 };
 
 /**
@@ -45,18 +50,31 @@ tree.Definition.prototype.inherit_from = function(definition) {
 };
 
 tree.Definition.prototype.toXML = function() {
-    var rules = this.rules.map(function(rule) {
+    var sym = this.symbolizers();
+    if (sym.length !== 1) {
+        throw {
+            message: 'A single symbolizer is expected'
+            + 'in definition compilation'
+        }
+    } else { sym = sym[0]; }
+
+    var symname = sym.charAt(0).toUpperCase()
+        + sym.slice(1).replace(/\-./, function(str) {
+        return str[1].toUpperCase();
+    }) + 'Symbolizer';
+    var rules = '    <' + symname + ' ' + this.rules.map(function(rule) {
         return rule.toCSS();
-    });
+    }).join('\n      ') + '/>';
+
     
     var filters = this.selector.filters.map(function(filter) {
         return filter.toXML();
     });
     
-    return  '    <Rule>\n' +
+    return  '  <Rule>\n    ' +
                   filters.join('\n        ') + '\n' +
-                  rules.join('\n') +
-            '\n    </Rule>\n';
+                  rules +
+            '\n  </Rule>\n';
 };
 
 })(require('mess/tree'));