diff --git a/code/extensions/GridFieldSortableObject.php b/code/extensions/GridFieldSortableObject.php
index 62ab8f0..7e1e425 100644
--- a/code/extensions/GridFieldSortableObject.php
+++ b/code/extensions/GridFieldSortableObject.php
@@ -1,4 +1,7 @@
 <?php
+/**
+ * @package extensions
+ */
 class GridFieldSortableObject extends DataExtension {
     public static $db=array(
                             'SortOrder'=>'Int'
@@ -8,12 +11,22 @@ class GridFieldSortableObject extends DataExtension {
     protected static $many_many_sortable_relations = array();
     protected static $sort_dir = "ASC";
     
-    
+    /**
+     * Sets the direction of the sort, by default it is ASC
+     * @param {string} $dir Sort direction ASC or DESC
+     */
     public static function set_sort_dir($dir) {
+        if(strtoupper($dir)!='ASC' && strtoupper($dir)!='DESC') {
+            user_error('Sort direction must be ASC or DESC', E_USER_ERROR);
+        }
+        
         self::$sort_dir=$dir;
     }
-
-
+    
+    /**
+     * Makes a class sortable
+     * @param {string} $className Name of the DataObject to extend
+     */
     public static function add_sortable_class($className) {
         if(!self::is_sortable_class($className)) {
             Object::add_extension($className, 'GridFieldSortableObject');
@@ -21,7 +34,12 @@ class GridFieldSortableObject extends DataExtension {
             self::$sortable_classes[]=$className;
         }
     }
-
+    
+    /**
+     * Makes a many_many relationship sortable
+     * @param {string} $ownerClass Name of the owner class of the relationship
+     * @param {string} $componentName Name of the relationship
+     */
     public static function add_sortable_many_many_relation($ownerClass, $componentName) {
         list($parentClass, $componentClass, $parentField, $componentField, $table)=singleton($ownerClass)->many_many($componentName);
         
@@ -40,25 +58,31 @@ class GridFieldSortableObject extends DataExtension {
         self::add_sortable_class($componentClass);
     }
     
-    public static function remove_sortable_class($class) {
-        Object::remove_extension($class, 'GridFieldSortableObject');
-    }
-    
-    public static function is_sortable_class($classname) {
+    /**
+     * Checks to see if a given DataObject class is sortable or not
+     * @param {string} $className Name of the DataObject to check
+     */
+    public static function is_sortable_class($className) {
         if(in_array($classname, self::$sortable_classes)) {
             return true;
         }
         
         foreach(self::$sortable_classes as $class) {
-            if(is_subclass_of($classname, $class)) {
+            if(is_subclass_of($className, $class)) {
                 return true;
             }
         }
         
         
-        return Object::has_extension($classname, 'GridFieldSortableObject');
+        return Object::has_extension($className, 'GridFieldSortableObject');
     }
     
+    /**
+     * Checks to see if a given many_many relationship is sortable or not
+     * @param {string} $componentClass Name of the component's class
+     * @param {string} $parentClass Name of the owner class of the relationship
+     * @return {bool} Returns boolean true if the many_many relationship is sortable
+     */
     public static function is_sortable_many_many($componentClass, $parentClass=null) {
         $map=self::$many_many_sortable_relations;
         if($parentClass===null) {
@@ -73,14 +97,22 @@ class GridFieldSortableObject extends DataExtension {
 
     }
     
-    public static function get_join_tables($classname) {
-        if(isset(self::$many_many_sortable_relations[$classname])) {
-            return self::$many_many_sortable_relations[$classname];
+    /**
+     * Gets the join tables for the given class name
+     * @param {string} $className Name of the DataObject to fetch for
+     */
+    public static function get_join_tables($className) {
+        if(isset(self::$many_many_sortable_relations[$className])) {
+            return self::$many_many_sortable_relations[$className];
         }
         
         return false;
     }
     
+    /**
+     * Modifies the SQL appending the SortOrder with the direction to the orderby statement
+     * @param {SQLQuery} $query SQL Query to adjust
+     */
     public function augmentSQL(SQLQuery &$query) {
         if(empty($query->select) || $query->delete || in_array("COUNT(*)", $query->select) || in_array("count(*)", $query->select)) {
             return;
@@ -118,6 +150,9 @@ class GridFieldSortableObject extends DataExtension {
         }
     }
     
+    /**
+     * Sets the sort order on the DataObject when its being written to the database for the first time
+     */
     public function onBeforeWrite() {
         if(!$this->owner->ID) {
             if($peers=DataList::create($this->owner->class)) {
diff --git a/code/forms/GridFieldSortableRows.php b/code/forms/GridFieldSortableRows.php
index 12df673..bb3fa17 100644
--- a/code/forms/GridFieldSortableRows.php
+++ b/code/forms/GridFieldSortableRows.php
@@ -132,10 +132,10 @@ class GridFieldSortableRows implements GridField_HTMLProvider, GridField_ActionP
         for($sort=0;$sort<count($data['Items']);$sort++) {
             $id=intval($data['Items'][$sort]);
             if($many_many) {
-                DB::query("UPDATE \"$table\" SET \"SortOrder\" = $sort WHERE \"{$className}ID\" = $id AND \"{$ownerClass}ID\" = $controllerID");
+                DB::query('UPDATE "'.$table.'" SET "SortOrder" = '.($sort+1).' WHERE "'.$className.'ID" = $id AND "'.$ownerClass.'ID" = '.$controllerID);
             }else {
                 $obj=DataObject::get_by_id($className, $id);
-                $obj->SortOrder=$sort;
+                $obj->SortOrder=$sort+1;
                 $obj->write();
             }
         }