diff --git a/lib/carto/functions.js b/lib/carto/functions.js
index 012f140..e16867a 100644
--- a/lib/carto/functions.js
+++ b/lib/carto/functions.js
@@ -12,6 +12,25 @@ tree.functions = {
     hsl: function (h, s, l) {
         return this.hsla(h, s, l, 1.0);
     },
+    // Only require val
+    stop: function (val) {
+        if (arguments.length > 1) var color = arguments[1];
+        if (arguments.length > 2) var mode = arguments[2];
+
+        return {
+            is: 'tag',
+            val: val,
+            color: color,
+            mode: mode,
+            toString: function(env) {
+                return '\n\t<stop value="' + val.eval(env) + '"' +
+                    (color ? ' color="' + color.eval(env) + '" ' : '') +
+                    (mode ? ' mode="' + mode.eval(env) + '" ' : '') +
+                    '/>';
+
+            }
+        };
+    },
     hsla: function (h, s, l, a) {
         h = (number(h) % 360) / 360;
         s = number(s); l = number(l); a = number(a);
diff --git a/lib/carto/tree/call.js b/lib/carto/tree/call.js
index 380dfae..8e03b59 100644
--- a/lib/carto/tree/call.js
+++ b/lib/carto/tree/call.js
@@ -6,6 +6,7 @@
 tree.Call = function Call(name, args, index) {
     this.name = name;
     this.args = args;
+    this.is = 'call';
     this.index = index;
 };
 tree.Call.prototype = {
@@ -34,7 +35,7 @@ tree.Call.prototype = {
         }
 
         if (this.name in tree.functions) { // 1.
-            if (tree.functions[this.name].length === args.length) {
+            if (tree.functions[this.name].length < args.length) {
                 return tree.functions[this.name].apply(tree.functions, args);
             } else {
                 env.error({
diff --git a/lib/carto/tree/definition.js b/lib/carto/tree/definition.js
index 3a443ab..05e11ba 100644
--- a/lib/carto/tree/definition.js
+++ b/lib/carto/tree/definition.js
@@ -111,6 +111,9 @@ tree.Definition.prototype.symbolizersToXML = function(env, symbolizers, zoom) {
             if (x && x.serialization && x.serialization === 'content') {
                 selfclosing = false;
                 tagcontent = attributes[key].eval(env).toXML(env, true);
+            } else if (x && x.serialization && x.serialization === 'tag') {
+                selfclosing = false;
+                tagcontent = attributes[key].eval(env).toXML(env, true);
             } else {
                 xml += attributes[key].eval(env).toXML(env) + ' ';
             }
diff --git a/lib/carto/tree/reference.js b/lib/carto/tree/reference.js
index 55deadf..aeaa685 100644
--- a/lib/carto/tree/reference.js
+++ b/lib/carto/tree/reference.js
@@ -113,6 +113,12 @@ tree.Reference.validValue = function(env, selector, value) {
                 }
             }
             return true;
+        } else if (tree.Reference.selector(selector).type == 'tags') {
+            if (!value.value) return false;
+            for (i = 0; i < value.value[0].value.length; i++) {
+                if (value.value[0].value[i].is !== 'tag') return false;
+            }
+            return true;
         } else {
             if (tree.Reference.selector(selector).validate) {
                 var valid = false;
diff --git a/lib/carto/tree/reference.json b/lib/carto/tree/reference.json
index 449b705..cffc0b3 100644
--- a/lib/carto/tree/reference.json
+++ b/lib/carto/tree/reference.json
@@ -575,6 +575,28 @@
                     "gaussian",
                     "lanczos"
                 ]
+            },
+            "colorizer-default-mode": {
+                "css": "raster-colorizer-default-mode",
+                "type": [
+                    "discrete",
+                    "linear",
+                    "exact"
+                ]
+            },
+            "colorizer-default-color": {
+                "css": "raster-colorizer-default-color",
+                "type": "color"
+            },
+            "colorizer-epsilon": {
+                "css": "raster-colorizer-epsilon",
+                "type": "float"
+            },
+            "stop": {
+                "css": "raster-colorizer-stops",
+                "type": "tags",
+                "serialization": "tag",
+                "tagname": "tagname"
             }
         },
         "point": {
diff --git a/test/rendering/rastercolorizer.mss b/test/rendering/rastercolorizer.mss
index d362363..988e12f 100644
--- a/test/rendering/rastercolorizer.mss
+++ b/test/rendering/rastercolorizer.mss
@@ -3,5 +3,8 @@
   raster-colorizer-default-mode:discrete;
   raster-colorizer-default-color:#f00;
   raster-colorizer-epsilon:0.05;
-  raster-colorizer-stops:stop(5, #ff0, "linear");
+  raster-colorizer-stops:
+    stop(5, #f00)
+    stop(10, #f40, linear)
+    stop(10, #f80);
 }