diff --git a/library/HTMLPurifier/HTMLDefinition.php b/library/HTMLPurifier/HTMLDefinition.php
index 0efa7f74..00bcface 100644
--- a/library/HTMLPurifier/HTMLDefinition.php
+++ b/library/HTMLPurifier/HTMLDefinition.php
@@ -357,6 +357,11 @@ class HTMLPurifier_HTMLDefinition
         //////////////////////////////////////////////////////////////////////
         // info[]->type : defines the type of the element (block or inline)
         
+        // unknown until proven inline/block
+        foreach ($this->info as $i => $x) {
+            $this->info[$i]->type = 'unknown';
+        }
+        
         // reuses $e_Inline and $e_Block
         foreach ($e_Inline->elements as $name => $bool) {
             if ($name == '#PCDATA') continue;
@@ -642,13 +647,13 @@ class HTMLPurifier_ElementDef
     var $child;
     
     var $content_model;
-    var $content_model_type = 'optional';
+    var $content_model_type;
     
     /**
      * Type of the tag: inline or block or unknown?
      * @public
      */
-    var $type = 'unknown';
+    var $type;
     
     /**
      * Lookup table of tags excluded from all descendants of this tag.
@@ -658,4 +663,4 @@ class HTMLPurifier_ElementDef
     
 }
 
-?>
+?>
\ No newline at end of file
diff --git a/library/HTMLPurifier/HTMLModule/Hypertext.php b/library/HTMLPurifier/HTMLModule/Hypertext.php
index 10b05bf8..37e29653 100644
--- a/library/HTMLPurifier/HTMLModule/Hypertext.php
+++ b/library/HTMLPurifier/HTMLModule/Hypertext.php
@@ -26,6 +26,7 @@ class HTMLPurifier_HTMLModule_Hypertext extends HTMLPurifier_HTMLModule
             //'type' => 'ContentType',
         );
         $this->info['a']->content_model = '#PCDATA | Inline';
+        $this->info['a']->content_model_type = 'optional';
         $this->info['a']->excludes = array('a' => true);
     }
     
diff --git a/library/HTMLPurifier/HTMLModule/List.php b/library/HTMLPurifier/HTMLModule/List.php
new file mode 100644
index 00000000..fa32029e
--- /dev/null
+++ b/library/HTMLPurifier/HTMLModule/List.php
@@ -0,0 +1,40 @@
+<?php
+
+require_once 'HTMLPurifier/HTMLModule.php';
+
+/**
+ * XHTML 1.1 List Module, defines list-oriented elements.
+ */
+class HTMLPurifier_HTMLModule_List extends HTMLPurifier_HTMLModule
+{
+    
+    var $elements = array('dl', 'dt', 'dd', 'ol', 'ul', 'li');
+    var $info = array();
+    // technically speaking, the List content set is a fully formed
+    // one or more expr, but it invariably occurs in an optional declaration
+    // so we're not going to do that subtlety. It might cause trouble
+    // if a user defines "List" and expects that multiple lists are
+    // allowed to be specified, but then again, that's not very intuitive.
+    var $content_sets = array('List' => 'dl | ol | ul', 'Flow' => 'List');
+    
+    function HTMLPurifier_HTMLModule_List() {
+        foreach ($this->elements as $element) {
+            $this->info[$element] = new HTMLPurifier_ElementDef();
+            $this->info[$element]->attr = array(0 => array('Common'));
+            if ($element == 'li' || $element == 'dd') {
+                $this->info[$element]->content_model = '#PCDATA | Flow';
+                $this->info[$element]->content_model_type = 'optional';
+            } elseif ($element == 'ol' || $element == 'ul') {
+                $this->info[$element]->content_model = 'li';
+                $this->info[$element]->content_model_type = 'required';
+            }
+        }
+        $this->info['dt']->content_model = '#PCDATA | Inline';
+        $this->info['dt']->content_model_type = 'optional';
+        $this->info['dl']->content_model = 'dt | dd';
+        $this->info['dl']->content_model_type = 'required';
+    }
+    
+}
+
+?>
\ No newline at end of file
diff --git a/library/HTMLPurifier/HTMLModule/Text.php b/library/HTMLPurifier/HTMLModule/Text.php
index dbbdf718..12c91072 100644
--- a/library/HTMLPurifier/HTMLModule/Text.php
+++ b/library/HTMLPurifier/HTMLModule/Text.php
@@ -40,8 +40,10 @@ class HTMLPurifier_HTMLModule_Text extends HTMLPurifier_HTMLModule
                 $this->info[$element]->content_model_type = 'strictblockquote';
             } elseif ($element == 'div') {
                 $this->info[$element]->content_model = '#PCDATA | Flow';
+                $this->info[$element]->content_model_type = 'optional';
             } else {
                 $this->info[$element]->content_model = '#PCDATA | Inline';
+                $this->info[$element]->content_model_type = 'optional';
             }
         }
     }
diff --git a/library/HTMLPurifier/Printer/HTMLDefinition.php b/library/HTMLPurifier/Printer/HTMLDefinition.php
index e0c6bf29..20671912 100644
--- a/library/HTMLPurifier/Printer/HTMLDefinition.php
+++ b/library/HTMLPurifier/Printer/HTMLDefinition.php
@@ -29,6 +29,7 @@ class HTMLPurifier_Printer_HTMLDefinition extends HTMLPurifier_Printer
         $ret .= $this->element('caption', 'Environment');
         
         $ret .= $this->row('Parent of fragment', $def->info_parent);
+        $ret .= $this->renderChildren($def->info_parent_def->child);
         $ret .= $this->row('Strict mode', $def->strict);
         if ($def->strict) $ret .= $this->row('Block wrap name', $def->info_block_wrapper);
         
@@ -37,8 +38,6 @@ class HTMLPurifier_Printer_HTMLDefinition extends HTMLPurifier_Printer
             $ret .= $this->element('td', $this->listifyAttr($def->info_global_attr),0,0);
         $ret .= $this->end('tr');
         
-        $ret .= $this->renderChildren($def->info_parent_def->child);
-        
         $ret .= $this->start('tr');
             $ret .= $this->element('th', 'Tag transforms');
             $list = array();
diff --git a/library/HTMLPurifier/XHTMLDefinition.php b/library/HTMLPurifier/XHTMLDefinition.php
index 1420ccb2..bc35bf0e 100644
--- a/library/HTMLPurifier/XHTMLDefinition.php
+++ b/library/HTMLPurifier/XHTMLDefinition.php
@@ -4,9 +4,11 @@ require_once 'HTMLPurifier/HTMLDefinition.php';
 
 require_once 'HTMLPurifier/AttrTypes.php';
 require_once 'HTMLPurifier/AttrCollection.php';
+
 require_once 'HTMLPurifier/HTMLModule.php';
 require_once 'HTMLPurifier/HTMLModule/Text.php';
 require_once 'HTMLPurifier/HTMLModule/Hypertext.php';
+require_once 'HTMLPurifier/HTMLModule/List.php';
 
 /**
  * Next-generation HTML definition that will supplant HTMLPurifier_HTMLDefinition
@@ -22,6 +24,7 @@ class HTMLPurifier_XHTMLDefinition extends HTMLPurifier_HTMLDefinition
         
         $this->modules['Text'] = new HTMLPurifier_HTMLModule_Text();
         $this->modules['Hypertext'] = new HTMLPurifier_HTMLModule_Hypertext();
+        $this->modules['List'] = new HTMLPurifier_HTMLModule_List();
         
         $this->attr_types = new HTMLPurifier_AttrTypes();
         $this->attr_collection = new HTMLPurifier_AttrCollection();
@@ -107,6 +110,7 @@ class HTMLPurifier_XHTMLDefinition extends HTMLPurifier_HTMLDefinition
             case 'custom':
                 return new HTMLPurifier_ChildDef_Custom($value);
         }
+        if ($value) return new HTMLPurifier_ChildDef_Optional($value);
         return HTMLPurifier_ChildDef_Empty();
     }