diff --git a/library/HTMLPurifier/AttrDef/MathML/Character.php b/library/HTMLPurifier/AttrDef/MathML/Character.php
new file mode 100644
index 00000000..94248c55
--- /dev/null
+++ b/library/HTMLPurifier/AttrDef/MathML/Character.php
@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * Validates the MathML attribute character.
+ */
+
+class HTMLPurifier_AttrDef_MathML_Character extends HTMLPurifier_AttrDef
+{
+
+    /**
+     * @param string $char
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return bool|string
+     */
+    public function validate($char, $config, $context)
+    {
+        if (mb_strlen($char) == 1 && strpos(' \t\n\r', $char) === false) {
+            return $char;
+        } elseif (preg_match('/&((#[0-9]+)|(#x[0-9A-Fa-f]+)|([0-9A-Za-z]+));/', $char)) {
+            return $char;
+        }
+        return false;
+    }
+}
\ No newline at end of file
diff --git a/library/HTMLPurifier/AttrDef/MathML/Color.php b/library/HTMLPurifier/AttrDef/MathML/Color.php
new file mode 100644
index 00000000..d5d796cf
--- /dev/null
+++ b/library/HTMLPurifier/AttrDef/MathML/Color.php
@@ -0,0 +1,44 @@
+<?php
+
+/**
+ * Validates Color as defined by MathML.
+ */
+class HTMLPurifier_AttrDef_MathML_Color extends HTMLPurifier_AttrDef
+{
+
+    // MathML 3 only accepts HTML4 color names + transparent
+    static protected $colornames = array(
+        'aqua',
+        'black',
+        'blue',
+        'fuchsia',
+        'gray',
+        'green',
+        'lime',
+        'maroon',
+        'navy',
+        'olive',
+        'purple',
+        'red',
+        'silver',
+        'teal',
+        'white',
+        'yellow',
+        'transparent'
+    );
+
+    public function validate($color, $config, $context)
+    {
+
+        $color = trim($color);
+
+        if (preg_match('/(#[0-9A-Fa-f]{3})|(#[0-9A-Fa-f]{6})/', $color) || in_array(strtolower($color), static::$colornames)) {
+            return $color;
+        }
+
+        return false;
+    }
+
+}
+
+// vim: et sw=4 sts=4
diff --git a/library/HTMLPurifier/AttrDef/MathML/Length.php b/library/HTMLPurifier/AttrDef/MathML/Length.php
new file mode 100644
index 00000000..98daee94
--- /dev/null
+++ b/library/HTMLPurifier/AttrDef/MathML/Length.php
@@ -0,0 +1,36 @@
+<?php
+
+/**
+ * Validates the MathML type length (not to be confused with either HTML nor
+ * CSS's length).
+ */
+
+class HTMLPurifier_AttrDef_MathML_Length extends HTMLPurifier_AttrDef
+{
+
+    /**
+     * @param string $string
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return bool|string
+     */
+    public function validate($string, $config, $context)
+    {
+        $string = $this->parseCDATA($string);
+
+        // Optimizations
+        if ($string === '') {
+            return false;
+        }
+        if ($string === '0') {
+            return '0';
+        }
+
+        $length = HTMLPurifier_MathMLLength::make($string);
+        if (!$length->isValid()) {
+            return false;
+        }
+
+        return $length->toString();
+    }
+}
\ No newline at end of file
diff --git a/library/HTMLPurifier/AttrTypes.php b/library/HTMLPurifier/AttrTypes.php
index 3b70520b..069137e5 100644
--- a/library/HTMLPurifier/AttrTypes.php
+++ b/library/HTMLPurifier/AttrTypes.php
@@ -50,10 +50,23 @@ class HTMLPurifier_AttrTypes
 
         // "proprietary" types
         $this->info['Class'] = new HTMLPurifier_AttrDef_HTML_Class();
+        $this->info['CSS'] = new HTMLPurifier_AttrDef_CSS();
 
         // number is really a positive integer (one or more digits)
         // FIXME: ^^ not always, see start and value of list items
         $this->info['Number']   = new HTMLPurifier_AttrDef_Integer(false, false, true);
+
+        // MathML types
+        $this->info['MathML_ID'] = new HTMLPurifier_AttrDef_MathML_ID();
+        $this->info['MathML_Length'] = new HTMLPurifier_AttrDef_MathML_Length();
+        $this->info['MathML_UnsignedInteger'] = new HTMLPurifier_AttrDef_Integer(false, true, true);
+        $this->info['MathML_PositiveInteger'] = new HTMLPurifier_AttrDef_Integer(false, false, true);
+        $this->info['MathML_Integer'] = new HTMLPurifier_AttrDef_Integer(true, true, true);
+        $this->info['MathML_UnsignedNumber'] = new HTMLPurifier_AttrDef_CSS_Number(true);
+        $this->info['MathML_Number'] = new HTMLPurifier_AttrDef_CSS_Number(false);
+        $this->info['MathML_Character'] = new HTMLPurifier_AttrDef_MathML_Character();
+        $this->info['MathML_Color'] = new HTMLPurifier_AttrDef_MathML_Color();
+
     }
 
     private static function makeEnum($in)
diff --git a/library/HTMLPurifier/HTMLModule/MathML.php b/library/HTMLPurifier/HTMLModule/MathML.php
index c4e9cf18..170b3ba2 100644
--- a/library/HTMLPurifier/HTMLModule/MathML.php
+++ b/library/HTMLPurifier/HTMLModule/MathML.php
@@ -82,10 +82,10 @@ class HTMLPurifier_HTMLModule_MathML extends HTMLPurifier_HTMLModule
                 $E['XLINK.prefix'] . ':type' => 'CDATA',
                 'xml:lang' => 'CDATA',
                 'xml:space' => 'Enum#default,preserve',
-                'id' => new HTMLPurifier_AttrDef_MathML_ID(), // MathML allows multiple elements with same ID
-                'xref' => new HTMLPurifier_AttrDef_MathML_ID(),
+                'id' => 'MathML_ID', // MathML allows multiple elements with same ID
+                'xref' => 'MathML_ID',
                 'class' => 'Class',
-                'style' => new HTMLPurifier_AttrDef_CSS(),
+                'style' => 'CSS',
                 'href' => 'URI',
                 'other' => 'CDATA',
             ),
@@ -1442,16 +1442,16 @@ class HTMLPurifier_HTMLModule_MathML extends HTMLPurifier_HTMLModule
         $E['mpadded-length'] = 'CDATA';
         $E['linestyle'] = 'Enum#none,solid,dashed';
         $E['columnalignstyle'] = 'Enum#left,center,right';
-        $E['unsigned-integer'] = 'CDATA';
-        $E['integer'] = 'CDATA';
-        $E['number'] = 'CDATA';
-        $E['character'] = 'CDATA';
-        $E['color'] = 'CDATA';
-        $E['positive-integer'] = 'CDATA';
+        $E['unsigned-integer'] = 'MathML_UnsignedInteger';
+        $E['integer'] = 'MathML_Integer';
+        $E['number'] = 'MathML_Number';
+        $E['character'] = 'MathML_Character';
+        $E['color'] = 'MathML_Color';
+        $E['positive-integer'] = 'MathML_PositiveInteger';
 
         $E['token.content'] = '#PCDATA|mglyph|malignmark';
 
-        $E['length'] = 'CDATA';
+        $E['length'] = 'MathML_Length';
         $E['DeprecatedTokenAtt'] = array(
             'fontfamily' => 'CDATA',
             'fontweight' => 'Enum#normal,bold',
@@ -2167,7 +2167,8 @@ class HTMLPurifier_HTMLModule_MathML extends HTMLPurifier_HTMLModule
             array_merge(
                 $CCPAtt,
                 array(
-                    'actiontype*' => 'CDATA',
+                    // Using 'actiontype*' removes maction element altogether 
+                    'actiontype' => 'CDATA',
                     'selection' => $E['positive-integer'],
                 )
             )
diff --git a/library/HTMLPurifier/Length.php b/library/HTMLPurifier/Length.php
index e70da55a..4b5e2562 100644
--- a/library/HTMLPurifier/Length.php
+++ b/library/HTMLPurifier/Length.php
@@ -81,7 +81,8 @@ class HTMLPurifier_Length
         if (!ctype_lower($this->unit)) {
             $this->unit = strtolower($this->unit);
         }
-        if (!isset(HTMLPurifier_Length::$allowedUnits[$this->unit])) {
+        if (!isset(static::$allowedUnits[$this->unit]) &&
+            !(isset(static::$allowedUnits['']) && $this->unit === false)) {
             return false;
         }
         // Hack:
diff --git a/library/HTMLPurifier/MathMLLength.php b/library/HTMLPurifier/MathMLLength.php
new file mode 100644
index 00000000..ecdef7fc
--- /dev/null
+++ b/library/HTMLPurifier/MathMLLength.php
@@ -0,0 +1,136 @@
+<?php
+
+/**
+ * Represents a length in MathML. These admit namedspace values.
+ */
+class HTMLPurifier_MathMLLength extends HTMLPurifier_Length
+{
+
+    /**
+     * One of the specified namedspaces.
+     * @type string
+     */
+    protected $namedspace;
+
+    /**
+    * Array Lookup array of namedspaces recognized by MathML
+    * @type array
+    */
+    protected static $allowedNamedspaces = array(
+        'veryverythinmathspace' => true,
+        'verythinmathspace' => true,
+        'thinmathspace' => true,
+        'mediummathspace' => true,
+        'thickmathspace' => true,
+        'verythickmathspace' => true,
+        'veryverythickmathspace' => true,
+        'negativeveryverythinmathspace' => true,
+        'negativeverythinmathspace' => true,
+        'negativethinmathspace' => true,
+        'negativemediummathspace' => true,
+        'negativethickmathspace' => true,
+        'negativeverythickmathspace' => true,
+        'negativeveryverythickmathspace' => true
+    );
+
+    /**
+     * Array Lookup array of units recognized by MathML.
+     * @note This is a restriction of HTMLPurifier_Length's allowed units.
+     * @type array
+     */
+    protected static $allowedUnits = array(
+        'em' => true, 'ex' => true, 'px' => true, 'in' => true,
+        'cm' => true, 'mm' => true, 'pt' => true, 'pc' => true,
+        '%' => true, '' => true
+    );
+
+    /**
+     * @param string $n Magnitude
+     * @param bool|string $u Unit
+     */
+    public function __construct($n = '0', $u = false, $namedspace = '')
+    {
+        if ($namedspace) {
+            $this->namedspace = strtolower($namedspace);
+        } else {
+            $this->n = (string) $n;
+            $this->unit = $u !== false ? (string) $u : false;
+        }
+    }
+
+    /**
+     * @param string $s Unit string, like '2em' or '3.4in', or namedspace
+     * @return HTMLPurifier_MathMLLength
+     * @warning Does not perform validation.
+     */
+    public static function make($s)
+    {
+        if ($s instanceof HTMLPurifier_MathMLLength) {
+            return $s;
+        }
+        if (isset(HTMLPurifier_MathMLLength::$allowedNamedspaces[trim($s)])) {
+            return new HTMLPurifier_MathMLLength('0', false, $s);
+        }
+        $length = HTMLPurifier_Length::make($s);
+        return new HTMLPurifier_MathMLLength($length->n, $length->unit);
+    }
+
+    /**
+     * Validates the number and unit or namedspace.
+     * @return bool
+     */
+    protected function validate()
+    {
+        if (isset(HTMLPurifier_MathMLLength::$allowedNamedspaces[$this->namedspace])) {
+            return true;
+        }
+        return parent::validate();
+    }
+
+    /**
+     * Returns string representation of number.
+     * @return string
+     */
+    public function toString()
+    {
+        if (!$this->isValid()) {
+            return false;
+        }
+        if ($this->namedspace) {
+            return $this->namedspace;
+        }
+        return parent::toString();
+    }
+
+    /**
+     * Retrieves the namedspace.
+     * @return string
+     */
+    public function getNamedspace()
+    {
+        return $this->namedspace;
+    }
+
+    /**
+     * Compares two lengths, and returns 1 if greater, -1 if less, 0 if equal
+     * and null if not comparable.
+     * @param HTMLPurifier_Length $l
+     * @return int
+     * @warning If both values are too large or small, this calculation will
+     *          not work properly
+     */
+    public function compareTo($l)
+    {
+        if ($l === false) {
+            return false;
+        }
+        if ($this->namedspace || $l->namedspace) {
+            if ($this->namedspace === $l->namedspace) {
+                return 0;
+            } else {
+                return null;
+            }
+        }
+        return parent::compareTo($l);
+    }
+}
\ No newline at end of file