diff --git a/library/HTMLPurifier/Strategy.php b/library/HTMLPurifier/Strategy.php
new file mode 100644
index 00000000..257e9364
--- /dev/null
+++ b/library/HTMLPurifier/Strategy.php
@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * Supertype for classes that define a strategy for modifying/purifying tokens.
+ * 
+ * While HTMLPurifier's core purpose is fixing HTML into something proper, 
+ * strategies provide plug points for extra configuration or even extra
+ * features, such as custom tags, custom parsing of text, etc.
+ */
+
+class HTMLPurifier_Strategy
+{
+    
+    /**
+     * Executes the strategy on the tokens.
+     * 
+     * @param $tokens Array of HTMLPurifier_Token objects to be operated on.
+     * @returns Processed array of token objects.
+     */
+    function execute($tokens) {
+        trigger_error('Cannot call abstract function', E_USER_ERROR);
+    }
+    
+}
+
+?>
\ No newline at end of file