diff --git a/library/HTMLPurifier/HTMLModule/Legacy.php b/library/HTMLPurifier/HTMLModule/Legacy.php
new file mode 100644
index 00000000..92674cf7
--- /dev/null
+++ b/library/HTMLPurifier/HTMLModule/Legacy.php
@@ -0,0 +1,24 @@
+<?php
+
+/**
+ * XHTML 1.1 Legacy module defines elements that were previously 
+ * deprecated.
+ * 
+ * @note Not all legacy elements have been implemented yet, which
+ *       is a bit of a reverse problem as compared to browsers!
+ * 
+ * This module can be used in combination with TransformToStrict in order
+ * to transform as many deprecated elements as possible, but retain
+ * questionably deprecated elements that do not have good alternatives
+ * as well as transform elements that don't have an implementation.
+ * See docs/ref-strictness.txt for more details.
+ */
+
+class HTMLPurifier_HTMLModule_Legacy extends HTMLPurifier_HTMLModule
+{
+    
+    // unimplemented
+    
+}
+
+?>
\ No newline at end of file
diff --git a/library/HTMLPurifier/HTMLModule/TransformToStrict.php b/library/HTMLPurifier/HTMLModule/TransformToStrict.php
new file mode 100644
index 00000000..a498eed4
--- /dev/null
+++ b/library/HTMLPurifier/HTMLModule/TransformToStrict.php
@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * Proprietary module that transforms deprecated elements into Strict
+ * HTML (see HTML 4.01 and XHTML 1.0) when possible.
+ */
+
+class HTMLPurifier_HTMLModule_TransformToStrict extends HTMLPurifier_HTMLModule
+{
+    
+    // unimplemented
+    
+}
+
+?>
\ No newline at end of file
diff --git a/library/HTMLPurifier/HTMLModule/TransformToXHTML11.php b/library/HTMLPurifier/HTMLModule/TransformToXHTML11.php
new file mode 100644
index 00000000..e3f7a13e
--- /dev/null
+++ b/library/HTMLPurifier/HTMLModule/TransformToXHTML11.php
@@ -0,0 +1,21 @@
+<?php
+
+/**
+ * Proprietary module that transforms XHTML 1.0 deprecated aspects into
+ * XHTML 1.1 compliant ones, when possible. For maximum effectiveness,
+ * HTMLPurifier_HTMLModule_TransformToStrict must also be loaded
+ * (otherwise, elements that were deprecated from Transitional to Strict
+ * will not be transformed).
+ * 
+ * XHTML 1.1 compliant document are automatically XHTML 1.0 compliant too,
+ * although they may not be as friendly to legacy browsers.
+ */
+
+class HTMLPurifier_HTMLModule_TransformToXHTML11 extends HTMLPurifier_HTMLModule
+{
+    
+    // unimplemented
+    
+}
+
+?>
\ No newline at end of file