diff --git a/library/HTMLPurifier/AttrTransform.php b/library/HTMLPurifier/AttrTransform.php
index 0b68df68..7edde559 100644
--- a/library/HTMLPurifier/AttrTransform.php
+++ b/library/HTMLPurifier/AttrTransform.php
@@ -23,9 +23,10 @@ class HTMLPurifier_AttrTransform
      * @param $attr Assoc array of attributes, usually from
      *              HTMLPurifier_Token_Tag::$attributes
      * @param $config Mandatory HTMLPurifier_Config object.
+     * @param $context Mandatory HTMLPurifier_Context object
      * @returns Processed attribute array.
      */
-    function transform($attr, $config) {
+    function transform($attr, $config, $context) {
         trigger_error('Cannot call abstract function', E_USER_ERROR);
     }
 }
diff --git a/library/HTMLPurifier/AttrTransform/BdoDir.php b/library/HTMLPurifier/AttrTransform/BdoDir.php
index a346bb18..dd20f26a 100644
--- a/library/HTMLPurifier/AttrTransform/BdoDir.php
+++ b/library/HTMLPurifier/AttrTransform/BdoDir.php
@@ -20,7 +20,7 @@ HTMLPurifier_ConfigSchema::defineAllowedValues(
 class HTMLPurifier_AttrTransform_BdoDir extends HTMLPurifier_AttrTransform
 {
     
-    function transform($attr, $config) {
+    function transform($attr, $config, $context) {
         if (isset($attr['dir'])) return $attr;
         $attr['dir'] = $config->get('Attr', 'DefaultTextDir');
         return $attr;
diff --git a/library/HTMLPurifier/AttrTransform/ImgRequired.php b/library/HTMLPurifier/AttrTransform/ImgRequired.php
index 8bb6fc3f..c943d696 100644
--- a/library/HTMLPurifier/AttrTransform/ImgRequired.php
+++ b/library/HTMLPurifier/AttrTransform/ImgRequired.php
@@ -25,7 +25,7 @@ HTMLPurifier_ConfigSchema::define(
 class HTMLPurifier_AttrTransform_ImgRequired extends HTMLPurifier_AttrTransform
 {
     
-    function transform($attr, $config) {
+    function transform($attr, $config, $context) {
         
         $src = true;
         if (!isset($attr['src'])) {
diff --git a/library/HTMLPurifier/AttrTransform/Lang.php b/library/HTMLPurifier/AttrTransform/Lang.php
index 384b7a7f..97fd8064 100644
--- a/library/HTMLPurifier/AttrTransform/Lang.php
+++ b/library/HTMLPurifier/AttrTransform/Lang.php
@@ -10,7 +10,7 @@ require_once 'HTMLPurifier/AttrTransform.php';
 class HTMLPurifier_AttrTransform_Lang extends HTMLPurifier_AttrTransform
 {
     
-    function transform($attr, $config) {
+    function transform($attr, $config, $context) {
         
         $lang     = isset($attr['lang']) ? $attr['lang'] : false;
         $xml_lang = isset($attr['xml:lang']) ? $attr['xml:lang'] : false;
diff --git a/library/HTMLPurifier/AttrTransform/TextAlign.php b/library/HTMLPurifier/AttrTransform/TextAlign.php
index 5e04c627..e42354a0 100644
--- a/library/HTMLPurifier/AttrTransform/TextAlign.php
+++ b/library/HTMLPurifier/AttrTransform/TextAlign.php
@@ -8,7 +8,7 @@ require_once 'HTMLPurifier/AttrTransform.php';
 class HTMLPurifier_AttrTransform_TextAlign
     extends HTMLPurifier_AttrTransform {
 
-    function transform($attr, $config) {
+    function transform($attr, $config, $context) {
         
         if (!isset($attr['align'])) return $attr;
         
diff --git a/library/HTMLPurifier/Strategy/ValidateAttributes.php b/library/HTMLPurifier/Strategy/ValidateAttributes.php
index 2aae1bd7..2924aed2 100644
--- a/library/HTMLPurifier/Strategy/ValidateAttributes.php
+++ b/library/HTMLPurifier/Strategy/ValidateAttributes.php
@@ -38,19 +38,17 @@ class HTMLPurifier_Strategy_ValidateAttributes extends HTMLPurifier_Strategy
             $attr = $token->attributes;
             
             // do global transformations (pre)
-            // ex. <ELEMENT lang="fr"> to <ELEMENT lang="fr" xml:lang="fr">
-            // DEFINITION CALL
+            // nothing currently utilizes this
             foreach ($definition->info_attr_transform_pre as $transform) {
-                $attr = $transform->transform($attr, $config);
+                $attr = $transform->transform($attr, $config, $context);
             }
             
             // do local transformations only applicable to this element (pre)
             // ex. <p align="right"> to <p style="text-align:right;">
-            // DEFINITION CALL
             foreach ($definition->info[$token->name]->attr_transform_pre
                 as $transform
             ) {
-                $attr = $transform->transform($attr, $config);
+                $attr = $transform->transform($attr, $config, $context);
             }
             
             // create alias to this element's attribute definition array, see
@@ -106,11 +104,15 @@ class HTMLPurifier_Strategy_ValidateAttributes extends HTMLPurifier_Strategy
             }
             
             // post transforms
+            
+            // ex. <x lang="fr"> to <x lang="fr" xml:lang="fr">
             foreach ($definition->info_attr_transform_post as $transform) {
-                $attr = $transform->transform($attr, $config);
+                $attr = $transform->transform($attr, $config, $context);
             }
+            
+            // ex. <bdo> to <bdo dir="ltr">
             foreach ($definition->info[$token->name]->attr_transform_post as $transform) {
-                $attr = $transform->transform($attr, $config);
+                $attr = $transform->transform($attr, $config, $context);
             }
             
             // commit changes
diff --git a/tests/HTMLPurifier/AttrTransformHarness.php b/tests/HTMLPurifier/AttrTransformHarness.php
index ceff33b7..689799c4 100644
--- a/tests/HTMLPurifier/AttrTransformHarness.php
+++ b/tests/HTMLPurifier/AttrTransformHarness.php
@@ -1,15 +1,20 @@
 <?php
 
+// todo: change testing harness from accepting arrays to 
+// have one call per test
+
 class HTMLPurifier_AttrTransformHarness extends UnitTestCase
 {
     
     var $transform;
     
-    function assertTransform($inputs, $expect, $config = array()) {
+    function assertTransform($inputs, $expect, $config = array(), $context = array()) {
         $default_config = HTMLPurifier_Config::createDefault();
+        $default_context = new HTMLPurifier_Context();
         foreach ($inputs as $i => $input) {
             if (!isset($config[$i])) $config[$i] = $default_config;
-            $result = $this->transform->transform($input, $config[$i]);
+            if (!isset($context[$i])) $context[$i] = $default_context;
+            $result = $this->transform->transform($input, $config[$i], $context[$i]);
             if ($expect[$i] === true) $expect[$i] = $input;
             $this->assertEqual($expect[$i], $result, "Test $i: %s");
         }