diff --git a/rnc/mathml4-core.rnc b/rnc/mathml4-core.rnc
index 253deb3..5926024 100644
--- a/rnc/mathml4-core.rnc
+++ b/rnc/mathml4-core.rnc
@@ -12,7 +12,7 @@ namespace h = "http://www.w3.org/1999/xhtml"
 
 start |= math
 
-math = element math {math.attributes,MathExpression*}
+math = element math {math.attributes,ImpliedMrow}
 
 MathMLoneventAttributes =
   attribute onabort {text}?,
@@ -179,7 +179,9 @@ MathExpression = TokenExpression|
                      mmultiscripts|mtable|maction|
 		     semantics
 
-ImpliedMrow = MathExpression*
+MathMalignExpression = MathExpression
+			   
+ImpliedMrow = MathMalignExpression*
 
 TableRowExpression = mtr
 
@@ -244,7 +246,7 @@ mprescripts = element mprescripts {mprescripts.attributes,empty}
 mprescripts.attributes = 
   MathMLPGlobalAttributes
 
-mrow = element mrow {mrow.attributes, MathExpression*}
+mrow = element mrow {mrow.attributes, ImpliedMrow}
 mrow.attributes = 
   MathMLPGlobalAttributes
 
@@ -337,7 +339,7 @@ mtd.attributes =
   attribute columnspan {xsd:positiveInteger}?
 
 
-maction = element maction {maction.attributes, MathExpression+}
+maction = element maction {maction.attributes, ImpliedMrow}
 maction.attributes = 
   MathMLPGlobalAttributes,
   attribute actiontype {text}?,
diff --git a/rnc/mathml4-legacy.rnc b/rnc/mathml4-legacy.rnc
index c2aa767..ae95edf 100644
--- a/rnc/mathml4-legacy.rnc
+++ b/rnc/mathml4-legacy.rnc
@@ -81,3 +81,33 @@ mspace.attributes &= DeprecatedTokenAtt
 ms.attributes &= DeprecatedTokenAtt
 
 semantics.attributes &= DefEncAtt
+
+
+# malignmark in tokens
+token.content |= malignmark
+# malignmark in mfrac etc
+MathExpression |= MalignExpression
+
+maligngroup.attributes |=
+  attribute groupalign {"left" | "center" | "right" | "decimalpoint"}?
+
+malignmark.attributes |=
+  attribute edge {"left" | "right"}?
+
+# groupalign
+group-alignment = "left" | "center" | "right" | "decimalpoint"
+group-alignment-list = list {group-alignment+}
+group-alignment-list-list = xsd:string {
+  pattern = '(\s*\{\s*(left|center|right|decimalpoint)(\s+(left|center|right|decimalpoint))*\})*\s*' }
+
+mstyle.generalattributes &=
+  attribute groupalign {group-alignment-list-list}?
+
+mtable.attributes &=
+  attribute groupalign {group-alignment-list-list}?
+
+mtr.attributes &=
+  attribute groupalign {group-alignment-list-list}?
+		       
+mtd.attributes &=
+  attribute groupalign {group-alignment-list}?
diff --git a/rnc/mathml4-presentation.rnc b/rnc/mathml4-presentation.rnc
index 8c9bef5..7465abe 100644
--- a/rnc/mathml4-presentation.rnc
+++ b/rnc/mathml4-presentation.rnc
@@ -34,14 +34,16 @@ MathMLPGlobalAttributes &=
                    attribute href {xsd:anyURI}?,
                    attribute other {text}?
 
+MathMalignExpression |= MalignExpression
+			    
 MathExpression |= PresentationExpression
 
 TableRowExpression |= mlabeledtr
 
 
-MstackExpression = MathExpression|mscarries|msline|msrow|msgroup
+MstackExpression = MathMalignExpression|mscarries|msline|msrow|msgroup
 
-MsrowExpression = MathExpression|none
+MsrowExpression = MathMalignExpression|none
 
 
 linestyle = "none" | "solid" | "dashed"
@@ -81,14 +83,10 @@ character = xsd:string {
   pattern = '\s*\S\s*'}
 
 
-group-alignment = "left" | "center" | "right" | "decimalpoint"
-group-alignment-list = list {group-alignment+}
-group-alignment-list-list = xsd:string {
-  pattern = '(\s*\{\s*(left|center|right|decimalpoint)(\s+(left|center|right|decimalpoint))*\})*\s*' }
 positive-integer = xsd:positiveInteger
 
 
-token.content |= mglyph|malignmark|text
+token.content |= mglyph|text
 
 
 
@@ -142,23 +140,17 @@ msline.attributes =
   attribute rightoverhang {length-percentage}?,
   attribute mslinethickness {length-percentage | "thin" | "medium" | "thick"}?
 
-
-
 MalignExpression = maligngroup|malignmark
 
 malignmark = element malignmark {malignmark.attributes, empty}
-malignmark.attributes = 
-  MathMLPGlobalAttributes,
-  attribute edge {"left" | "right"}?
+malignmark.attributes =  MathMLPGlobalAttributes
 
 
 maligngroup = element maligngroup {maligngroup.attributes, empty}
-maligngroup.attributes = 
-  MathMLPGlobalAttributes,
-  attribute groupalign {"left" | "center" | "right" | "decimalpoint"}?
+maligngroup.attributes = MathMLPGlobalAttributes
+  
 
-
-PresentationExpression = TokenExpression|MalignExpression|
+PresentationExpression = TokenExpression|
                          mrow|mfrac|msqrt|mroot|mstyle|merror|mpadded|mphantom|
                          mfenced|menclose|msub|msup|msubsup|munder|mover|munderover|
                          mmultiscripts|mtable|mstack|mlongdiv|maction
@@ -179,8 +171,8 @@ mstyle.attributes &=
   mstyle.generalattributes
 
 mstyle.specificattributes =
-  attribute scriptlevel {integer}?,
-  attribute displaystyle {"true" | "false"}?,
+  attribute Xscriptlevel {integer}?,
+  attribute Xdisplaystyle {"true" | "false"}?,
   attribute scriptsizemultiplier {number}?,
   attribute scriptminsize {length-percentage}?,
   attribute infixlinebreakstyle {"before" | "after" | "duplicate"}?,
@@ -211,7 +203,6 @@ mstyle.generalattributes =
   attribute form {"prefix" | "infix" | "postfix"}?,
   attribute frame {linestyle}?,
   attribute framespacing {list {length-percentage, length-percentage}}?,
-  attribute groupalign {group-alignment-list-list}?,
   attribute height {length-percentage}?,
   attribute indentalign {"left" | "center" | "right" | "auto" | "id"}?,
   attribute indentalignfirst {"left" | "center" | "right" | "auto" | "id" | "indentalign"}?,
@@ -267,7 +258,7 @@ math.attributes &= mstyle.specificattributes
 math.attributes &= mstyle.generalattributes
 math.attributes &= attribute overflow {"linebreak" | "scroll" | "elide" | "truncate" | "scale"}?
 
-mfenced = element mfenced {mfenced.attributes, MathExpression*}
+mfenced = element mfenced {mfenced.attributes, ImpliedMrow}
 mfenced.attributes = 
   MathMLPGlobalAttributes,
   attribute open {text}?,
@@ -306,7 +297,6 @@ mtable.attributes &=
     pattern ='\s*(top|bottom|center|baseline|axis)(\s+-?[0-9]+)?\s*'}}?,
   attribute rowalign {list {verticalalign+} }?,
   attribute columnalign {list {columnalignstyle+} }?,
-  attribute groupalign {group-alignment-list-list}?,
   attribute alignmentscope {list {("true" | "false") +}}?,
   attribute columnwidth {list {("auto" | length-percentage | "fit") +}}?,
   attribute width {"auto" | length-percentage}?,
@@ -332,15 +322,12 @@ mlabeledtr.attributes =
       
 mtr.attributes &= 
   attribute rowalign {"top" | "bottom" | "center" | "baseline" | "axis"}?,
-  attribute columnalign {list {columnalignstyle+} }?,
-  attribute groupalign {group-alignment-list-list}?
-
+  attribute columnalign {list {columnalignstyle+} }?
 
 
 mtd.attributes &= 
   attribute rowalign {"top" | "bottom" | "center" | "baseline" | "axis"}?,
-  attribute columnalign {columnalignstyle}?,
-  attribute groupalign {group-alignment-list}?
+  attribute columnalign {columnalignstyle}?
 
 
 mstack = element mstack {mstack.attributes, MstackExpression*}
diff --git a/rng/mathml4-content.rng b/rng/mathml4-content.rng
index 33e7326..97f20d2 100644
--- a/rng/mathml4-content.rng
+++ b/rng/mathml4-content.rng
@@ -133,10 +133,31 @@
       <data type="string"/>
     </attribute>
   </define>
-  <define name="CommonAtt" combine="choice">
+  <define name="math.attributes" combine="interleave">
+    <optional>
+      <attribute name="alttext"/>
+    </optional>
+  </define>
+  <define name="MathMLDataAttributes" combine="interleave">
+    <optional>
+      <attribute name="data-other"/>
+    </optional>
+  </define>
+  <define name="CommonAtt" combine="interleave">
     <zeroOrMore>
       <ref name="NonMathMLAtt"/>
     </zeroOrMore>
+    <ref name="MathMLDataAttributes"/>
+    <optional>
+      <attribute name="class">
+        <data type="NCName"/>
+      </attribute>
+    </optional>
+    <optional>
+      <attribute name="style">
+        <data type="string"/>
+      </attribute>
+    </optional>
     <optional>
       <attribute name="href">
         <data type="anyURI"/>
@@ -1244,10 +1265,10 @@
   <define name="nary-stats.class">
     <choice>
       <ref name="mean"/>
-      <ref name="sdev"/>
-      <ref name="variance"/>
       <ref name="median"/>
       <ref name="mode"/>
+      <ref name="sdev"/>
+      <ref name="variance"/>
     </choice>
   </define>
   <define name="ContExp" combine="choice">
@@ -1260,29 +1281,29 @@
       <empty/>
     </element>
   </define>
-  <define name="sdev">
-    <element name="sdev">
+  <define name="median">
+    <element name="median">
       <ref name="CommonAtt"/>
       <ref name="DefEncAtt"/>
       <empty/>
     </element>
   </define>
-  <define name="variance">
-    <element name="variance">
+  <define name="mode">
+    <element name="mode">
       <ref name="CommonAtt"/>
       <ref name="DefEncAtt"/>
       <empty/>
     </element>
   </define>
-  <define name="median">
-    <element name="median">
+  <define name="sdev">
+    <element name="sdev">
       <ref name="CommonAtt"/>
       <ref name="DefEncAtt"/>
       <empty/>
     </element>
   </define>
-  <define name="mode">
-    <element name="mode">
+  <define name="variance">
+    <element name="variance">
       <ref name="CommonAtt"/>
       <ref name="DefEncAtt"/>
       <empty/>
diff --git a/rng/mathml4-core.rng b/rng/mathml4-core.rng
index 1659f4e..266d108 100644
--- a/rng/mathml4-core.rng
+++ b/rng/mathml4-core.rng
@@ -17,12 +17,10 @@
   <define name="math">
     <element name="math">
       <ref name="math.attributes"/>
-      <zeroOrMore>
-        <ref name="MathExpression"/>
-      </zeroOrMore>
+      <ref name="ImpliedMrow"/>
     </element>
   </define>
-  <define name="htmloneventattributes">
+  <define name="MathMLoneventAttributes">
     <optional>
       <attribute name="onabort"/>
     </optional>
@@ -285,7 +283,38 @@
       <attribute name="onpaste"/>
     </optional>
   </define>
-  <define name="GlobalAttributes">
+  <!--
+    Sample set. May need preprocessing 
+    or schema extension to allow more see MathML Core (and HTML) spec
+  -->
+  <define name="MathMLDataAttributes">
+    <optional>
+      <attribute name="data-other"/>
+    </optional>
+  </define>
+  <!-- sample set, like data- may need preprocessing to allow more -->
+  <define name="MathMLARIAattributes">
+    <optional>
+      <attribute name="aria-label"/>
+    </optional>
+    <optional>
+      <attribute name="aria-describedby"/>
+    </optional>
+    <optional>
+      <attribute name="aria-details"/>
+    </optional>
+  </define>
+  <define name="MathMLintentAttributes">
+    <optional>
+      <attribute name="intent"/>
+    </optional>
+    <optional>
+      <attribute name="arg">
+        <data type="NCName"/>
+      </attribute>
+    </optional>
+  </define>
+  <define name="MathMLPGlobalAttributes">
     <optional>
       <attribute name="id">
         <data type="ID"/>
@@ -293,7 +322,7 @@
     </optional>
     <optional>
       <attribute name="class">
-        <data type="NMTOKENS"/>
+        <data type="NCName"/>
       </attribute>
     </optional>
     <optional>
@@ -301,14 +330,6 @@
         <data type="string"/>
       </attribute>
     </optional>
-    <optional>
-      <attribute name="intent"/>
-    </optional>
-    <optional>
-      <attribute name="arg">
-        <data type="NMTOKEN"/>
-      </attribute>
-    </optional>
     <optional>
       <attribute name="dir">
         <choice>
@@ -319,10 +340,7 @@
     </optional>
     <optional>
       <attribute name="mathbackground">
-        <choice>
-          <ref name="color"/>
-          <value>transparent</value>
-        </choice>
+        <ref name="color"/>
       </attribute>
     </optional>
     <optional>
@@ -352,9 +370,6 @@
         <data type="integer"/>
       </attribute>
     </optional>
-    <optional>
-      <attribute name="data-extra"/>
-    </optional>
     <optional>
       <attribute name="tabindex">
         <data type="integer"/>
@@ -363,10 +378,16 @@
     <optional>
       <attribute name="nonce"/>
     </optional>
-    <ref name="htmloneventattributes"/>
+    <ref name="MathMLoneventAttributes"/>
+    <!-- Extension attributes, no defined behavior -->
+    <ref name="MathMLDataAttributes"/>
+    <!-- No specified behavior in Core, see MathML4 -->
+    <ref name="MathMLintentAttributes"/>
+    <!-- No specified behavior in Core, see WAI-ARIA -->
+    <ref name="MathMLARIAattributes"/>
   </define>
   <define name="math.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="display">
         <choice>
@@ -375,10 +396,14 @@
         </choice>
       </attribute>
     </optional>
+    <optional>
+      <!-- No specified behavior in Core, see MathML4 -->
+      <attribute name="alttext"/>
+    </optional>
   </define>
   <define name="annotation">
     <element name="annotation">
-      <ref name="GlobalAttributes"/>
+      <ref name="MathMLPGlobalAttributes"/>
       <optional>
         <ref name="encoding"/>
       </optional>
@@ -413,7 +438,7 @@
     </element>
   </define>
   <define name="annotation-xml.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <ref name="encoding"/>
     </optional>
@@ -427,7 +452,7 @@
   </define>
   <define name="semantics">
     <element name="semantics">
-      <ref name="GlobalAttributes"/>
+      <ref name="semantics.attributes"/>
       <ref name="MathExpression"/>
       <zeroOrMore>
         <choice>
@@ -437,6 +462,9 @@
       </zeroOrMore>
     </element>
   </define>
+  <define name="semantics.attributes">
+    <ref name="MathMLPGlobalAttributes"/>
+  </define>
   <define name="mathml-boolean">
     <data type="string">
       <param name="pattern">\s*([Tt][Rr][Uu][Ee]|[Ff][Aa][Ll][Ss][Ee])\s*</param>
@@ -444,7 +472,7 @@
   </define>
   <define name="length-percentage">
     <data type="string">
-      <param name="pattern">\s*((-?[0-9]*([0-9]\.?|\.[0-9])[0-9]*(e[mx]|in|cm|mm|p[xtc]|%))|0)\s*</param>
+      <param name="pattern">\s*((-?[0-9]*([0-9]\.?|\.[0-9])[0-9]*(r?em|ex|in|cm|mm|p[xtc]|Q|v[hw]|vmin|vmax|%))|0)\s*</param>
     </data>
   </define>
   <define name="MathExpression">
@@ -470,9 +498,12 @@
       <ref name="semantics"/>
     </choice>
   </define>
+  <define name="MathMalignExpression">
+    <ref name="MathExpression"/>
+  </define>
   <define name="ImpliedMrow">
     <zeroOrMore>
-      <ref name="MathExpression"/>
+      <ref name="MathMalignExpression"/>
     </zeroOrMore>
   </define>
   <define name="TableRowExpression">
@@ -529,7 +560,7 @@
     </element>
   </define>
   <define name="mi.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="mn">
     <element name="mn">
@@ -538,7 +569,7 @@
     </element>
   </define>
   <define name="mn.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="mo">
     <element name="mo">
@@ -547,7 +578,7 @@
     </element>
   </define>
   <define name="mo.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="form">
         <choice>
@@ -589,7 +620,7 @@
     </optional>
     <optional>
       <attribute name="maxsize">
-        <ref name="maxsize-length"/>
+        <ref name="length-percentage"/>
       </attribute>
     </optional>
     <optional>
@@ -608,9 +639,6 @@
       </attribute>
     </optional>
   </define>
-  <define name="maxsize-length">
-    <ref name="length-percentage"/>
-  </define>
   <define name="mtext">
     <element name="mtext">
       <ref name="mtext.attributes"/>
@@ -618,7 +646,7 @@
     </element>
   </define>
   <define name="mtext.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="mspace">
     <element name="mspace">
@@ -627,7 +655,7 @@
     </element>
   </define>
   <define name="mspace.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="width">
         <ref name="length-percentage"/>
@@ -651,7 +679,7 @@
     </element>
   </define>
   <define name="ms.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="none">
     <element name="none">
@@ -660,7 +688,7 @@
     </element>
   </define>
   <define name="none.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="mprescripts">
     <element name="mprescripts">
@@ -669,18 +697,16 @@
     </element>
   </define>
   <define name="mprescripts.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="mrow">
     <element name="mrow">
       <ref name="mrow.attributes"/>
-      <zeroOrMore>
-        <ref name="MathExpression"/>
-      </zeroOrMore>
+      <ref name="ImpliedMrow"/>
     </element>
   </define>
   <define name="mrow.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="mfrac">
     <element name="mfrac">
@@ -690,7 +716,7 @@
     </element>
   </define>
   <define name="mfrac.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="linethickness">
         <ref name="length-percentage"/>
@@ -704,7 +730,7 @@
     </element>
   </define>
   <define name="msqrt.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="mroot">
     <element name="mroot">
@@ -714,7 +740,7 @@
     </element>
   </define>
   <define name="mroot.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="mstyle">
     <element name="mstyle">
@@ -723,7 +749,7 @@
     </element>
   </define>
   <define name="mstyle.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="merror">
     <element name="merror">
@@ -732,7 +758,7 @@
     </element>
   </define>
   <define name="merror.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="mpadded">
     <element name="mpadded">
@@ -741,7 +767,7 @@
     </element>
   </define>
   <define name="mpadded.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="height">
         <ref name="mpadded-length-percentage"/>
@@ -762,6 +788,11 @@
         <ref name="mpadded-length-percentage"/>
       </attribute>
     </optional>
+    <optional>
+      <attribute name="rspace">
+        <ref name="mpadded-length-percentage"/>
+      </attribute>
+    </optional>
     <optional>
       <attribute name="voffset">
         <ref name="mpadded-length-percentage"/>
@@ -778,7 +809,7 @@
     </element>
   </define>
   <define name="mphantom.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="msub">
     <element name="msub">
@@ -788,7 +819,7 @@
     </element>
   </define>
   <define name="msub.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="msup">
     <element name="msup">
@@ -798,7 +829,7 @@
     </element>
   </define>
   <define name="msup.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="msubsup">
     <element name="msubsup">
@@ -809,7 +840,7 @@
     </element>
   </define>
   <define name="msubsup.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="munder">
     <element name="munder">
@@ -819,7 +850,7 @@
     </element>
   </define>
   <define name="munder.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="accentunder">
         <ref name="mathml-boolean"/>
@@ -834,7 +865,7 @@
     </element>
   </define>
   <define name="mover.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="accent">
         <ref name="mathml-boolean"/>
@@ -850,7 +881,7 @@
     </element>
   </define>
   <define name="munderover.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="accent">
         <ref name="mathml-boolean"/>
@@ -889,7 +920,7 @@
     </element>
   </define>
   <define name="mtable.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="mtr">
     <element name="mtr">
@@ -900,7 +931,7 @@
     </element>
   </define>
   <define name="mtr.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="mtd">
     <element name="mtd">
@@ -909,7 +940,7 @@
     </element>
   </define>
   <define name="mtd.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="rowspan">
         <data type="positiveInteger"/>
@@ -924,13 +955,11 @@
   <define name="maction">
     <element name="maction">
       <ref name="maction.attributes"/>
-      <oneOrMore>
-        <ref name="MathExpression"/>
-      </oneOrMore>
+      <ref name="ImpliedMrow"/>
     </element>
   </define>
   <define name="maction.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="actiontype"/>
     </optional>
diff --git a/rng/mathml4-legacy.rng b/rng/mathml4-legacy.rng
index 7b6ebfe..bcb5956 100644
--- a/rng/mathml4-legacy.rng
+++ b/rng/mathml4-legacy.rng
@@ -207,9 +207,15 @@
     </optional>
     <optional>
       <attribute name="background">
+        <ref name="color"/>
+      </attribute>
+    </optional>
+    <optional>
+      <attribute name="mathsize">
         <choice>
-          <ref name="color"/>
-          <value>transparent</value>
+          <value>small</value>
+          <value>normal</value>
+          <value>big</value>
         </choice>
       </attribute>
     </optional>
@@ -238,4 +244,86 @@
   <define name="ms.attributes" combine="interleave">
     <ref name="DeprecatedTokenAtt"/>
   </define>
+  <define name="semantics.attributes" combine="interleave">
+    <ref name="DefEncAtt"/>
+  </define>
+  <!-- malignmark in tokens -->
+  <define name="token.content" combine="choice">
+    <ref name="malignmark"/>
+  </define>
+  <!-- malignmark in mfrac etc -->
+  <define name="MathExpression" combine="choice">
+    <ref name="MalignExpression"/>
+  </define>
+  <define name="maligngroup.attributes" combine="choice">
+    <optional>
+      <attribute name="groupalign">
+        <choice>
+          <value>left</value>
+          <value>center</value>
+          <value>right</value>
+          <value>decimalpoint</value>
+        </choice>
+      </attribute>
+    </optional>
+  </define>
+  <define name="malignmark.attributes" combine="choice">
+    <optional>
+      <attribute name="edge">
+        <choice>
+          <value>left</value>
+          <value>right</value>
+        </choice>
+      </attribute>
+    </optional>
+  </define>
+  <!-- groupalign -->
+  <define name="group-alignment">
+    <choice>
+      <value>left</value>
+      <value>center</value>
+      <value>right</value>
+      <value>decimalpoint</value>
+    </choice>
+  </define>
+  <define name="group-alignment-list">
+    <list>
+      <oneOrMore>
+        <ref name="group-alignment"/>
+      </oneOrMore>
+    </list>
+  </define>
+  <define name="group-alignment-list-list">
+    <data type="string">
+      <param name="pattern">(\s*\{\s*(left|center|right|decimalpoint)(\s+(left|center|right|decimalpoint))*\})*\s*</param>
+    </data>
+  </define>
+  <define name="mstyle.generalattributes" combine="interleave">
+    <optional>
+      <attribute name="groupalign">
+        <ref name="group-alignment-list-list"/>
+      </attribute>
+    </optional>
+  </define>
+  <define name="mtable.attributes" combine="interleave">
+    <optional>
+      <attribute name="groupalign">
+        <ref name="group-alignment-list-list"/>
+      </attribute>
+    </optional>
+  </define>
+  <define name="mtr.attributes" combine="interleave">
+    <optional>
+      <attribute name="groupalign">
+        <ref name="group-alignment-list-list"/>
+      </attribute>
+    </optional>
+  </define>
+  <define name="mtd.attributes" combine="interleave">
+    <optional>
+      <attribute name="groupalign">
+        <ref name="group-alignment-list"/>
+      </attribute>
+    </optional>
+  </define>
 </grammar>
diff --git a/rng/mathml4-presentation.rng b/rng/mathml4-presentation.rng
index 56dc540..620ff01 100644
--- a/rng/mathml4-presentation.rng
+++ b/rng/mathml4-presentation.rng
@@ -16,17 +16,12 @@
     <!-- named lengths -->
     <define name="length-percentage">
       <data type="string">
-        <param name="pattern">\s*((-?[0-9]*([0-9]\.?|\.[0-9])[0-9]*(e[mx]|in|cm|mm|p[xtc]|%))|0|(negative)?((very){0,2}thi(n|ck)|medium)mathspace)\s*</param>
+        <param name="pattern">\s*((-?[0-9]*([0-9]\.?|\.[0-9])[0-9]*(r?em|ex|in|cm|mm|p[xtc]|Q|v[hw]|vmin|vmax|%))|0|(negative)?((very){0,2}thi(n|ck)|medium)mathspace)\s*</param>
       </data>
     </define>
     <define name="mpadded-length-percentage">
       <data type="string">
-        <param name="pattern">\s*([\+\-]?[0-9]*([0-9]\.?|\.[0-9])[0-9]*\s*((%?\s*(height|depth|width)?)|e[mx]|in|cm|mm|p[xtc]|((negative)?((very){0,2}thi(n|ck)|medium)mathspace))?)\s*</param>
-      </data>
-    </define>
-    <define name="maxsize-length">
-      <data type="string">
-        <param name="pattern">\s*((-?[0-9]*([0-9]\.?|\.[0-9])[0-9]*(e[mx]|in|cm|mm|p[xtc]|%))|0|(negative)?((very){0,2}thi(n|ck)|medium)mathspace|infinity)\s*</param>
+        <param name="pattern">\s*([\+\-]?[0-9]*([0-9]\.?|\.[0-9])[0-9]*\s*((%?\s*(height|depth|width)?)|r?em|ex|in|cm|mm|p[xtc]|Q|v[hw]|vmin|vmax|%|((negative)?((very){0,2}thi(n|ck)|medium)mathspace))?)\s*</param>
       </data>
     </define>
   </include>
@@ -41,7 +36,7 @@
       <data type="string"/>
     </attribute>
   </define>
-  <define name="GlobalAttributes" combine="interleave">
+  <define name="MathMLPGlobalAttributes" combine="interleave">
     <zeroOrMore>
       <ref name="NonMathMLAtt"/>
     </zeroOrMore>
@@ -57,6 +52,9 @@
       <attribute name="other"/>
     </optional>
   </define>
+  <define name="MathMalignExpression" combine="choice">
+    <ref name="MalignExpression"/>
+  </define>
   <define name="MathExpression" combine="choice">
     <ref name="PresentationExpression"/>
   </define>
@@ -65,7 +63,7 @@
   </define>
   <define name="MstackExpression">
     <choice>
-      <ref name="MathExpression"/>
+      <ref name="MathMalignExpression"/>
       <ref name="mscarries"/>
       <ref name="msline"/>
       <ref name="msrow"/>
@@ -74,7 +72,7 @@
   </define>
   <define name="MsrowExpression">
     <choice>
-      <ref name="MathExpression"/>
+      <ref name="MathMalignExpression"/>
       <ref name="none"/>
     </choice>
   </define>
@@ -137,33 +135,12 @@
       <param name="pattern">\s*\S\s*</param>
     </data>
   </define>
-  <define name="group-alignment">
-    <choice>
-      <value>left</value>
-      <value>center</value>
-      <value>right</value>
-      <value>decimalpoint</value>
-    </choice>
-  </define>
-  <define name="group-alignment-list">
-    <list>
-      <oneOrMore>
-        <ref name="group-alignment"/>
-      </oneOrMore>
-    </list>
-  </define>
-  <define name="group-alignment-list-list">
-    <data type="string">
-      <param name="pattern">(\s*\{\s*(left|center|right|decimalpoint)(\s+(left|center|right|decimalpoint))*\})*\s*</param>
-    </data>
-  </define>
   <define name="positive-integer">
     <data type="positiveInteger"/>
   </define>
   <define name="token.content" combine="choice">
     <choice>
       <ref name="mglyph"/>
-      <ref name="malignmark"/>
       <text/>
     </choice>
   </define>
@@ -359,7 +336,7 @@
     </element>
   </define>
   <define name="mglyph.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="src">
         <data type="anyURI"/>
@@ -391,7 +368,7 @@
     </element>
   </define>
   <define name="msline.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="position">
         <ref name="integer"/>
@@ -436,15 +413,7 @@
     </element>
   </define>
   <define name="malignmark.attributes">
-    <ref name="GlobalAttributes"/>
-    <optional>
-      <attribute name="edge">
-        <choice>
-          <value>left</value>
-          <value>right</value>
-        </choice>
-      </attribute>
-    </optional>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="maligngroup">
     <element name="maligngroup">
@@ -453,22 +422,11 @@
     </element>
   </define>
   <define name="maligngroup.attributes">
-    <ref name="GlobalAttributes"/>
-    <optional>
-      <attribute name="groupalign">
-        <choice>
-          <value>left</value>
-          <value>center</value>
-          <value>right</value>
-          <value>decimalpoint</value>
-        </choice>
-      </attribute>
-    </optional>
+    <ref name="MathMLPGlobalAttributes"/>
   </define>
   <define name="PresentationExpression">
     <choice>
       <ref name="TokenExpression"/>
-      <ref name="MalignExpression"/>
       <ref name="mrow"/>
       <ref name="mfrac"/>
       <ref name="msqrt"/>
@@ -526,12 +484,12 @@
   </define>
   <define name="mstyle.specificattributes">
     <optional>
-      <attribute name="scriptlevel">
+      <attribute name="Xscriptlevel">
         <ref name="integer"/>
       </attribute>
     </optional>
     <optional>
-      <attribute name="displaystyle">
+      <attribute name="Xdisplaystyle">
         <choice>
           <value>true</value>
           <value>false</value>
@@ -767,11 +725,6 @@
         </list>
       </attribute>
     </optional>
-    <optional>
-      <attribute name="groupalign">
-        <ref name="group-alignment-list-list"/>
-      </attribute>
-    </optional>
     <optional>
       <attribute name="height">
         <ref name="length-percentage"/>
@@ -967,14 +920,6 @@
         </choice>
       </attribute>
     </optional>
-    <optional>
-      <attribute name="maxsize">
-        <choice>
-          <ref name="length-percentage"/>
-          <value>infinity</value>
-        </choice>
-      </attribute>
-    </optional>
     <optional>
       <attribute name="minlabelspacing">
         <ref name="length-percentage"/>
@@ -1168,13 +1113,11 @@
   <define name="mfenced">
     <element name="mfenced">
       <ref name="mfenced.attributes"/>
-      <zeroOrMore>
-        <ref name="MathExpression"/>
-      </zeroOrMore>
+      <ref name="ImpliedMrow"/>
     </element>
   </define>
   <define name="mfenced.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="open"/>
     </optional>
@@ -1192,7 +1135,7 @@
     </element>
   </define>
   <define name="menclose.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="notation"/>
     </optional>
@@ -1282,11 +1225,6 @@
         </list>
       </attribute>
     </optional>
-    <optional>
-      <attribute name="groupalign">
-        <ref name="group-alignment-list-list"/>
-      </attribute>
-    </optional>
     <optional>
       <attribute name="alignmentscope">
         <list>
@@ -1441,11 +1379,6 @@
         </list>
       </attribute>
     </optional>
-    <optional>
-      <attribute name="groupalign">
-        <ref name="group-alignment-list-list"/>
-      </attribute>
-    </optional>
   </define>
   <define name="mtd.attributes" combine="interleave">
     <optional>
@@ -1464,11 +1397,6 @@
         <ref name="columnalignstyle"/>
       </attribute>
     </optional>
-    <optional>
-      <attribute name="groupalign">
-        <ref name="group-alignment-list"/>
-      </attribute>
-    </optional>
   </define>
   <define name="mstack">
     <element name="mstack">
@@ -1479,7 +1407,7 @@
     </element>
   </define>
   <define name="mstack.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="align">
         <data type="string">
@@ -1555,7 +1483,7 @@
     </element>
   </define>
   <define name="msgroup.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="position">
         <ref name="integer"/>
@@ -1576,7 +1504,7 @@
     </element>
   </define>
   <define name="msrow.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="position">
         <ref name="integer"/>
@@ -1595,7 +1523,7 @@
     </element>
   </define>
   <define name="mscarries.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="position">
         <ref name="integer"/>
@@ -1645,7 +1573,7 @@
     </element>
   </define>
   <define name="mscarry.attributes">
-    <ref name="GlobalAttributes"/>
+    <ref name="MathMLPGlobalAttributes"/>
     <optional>
       <attribute name="location">
         <choice>
diff --git a/rng/mathml4.rng b/rng/mathml4.rng
index 11b3ddc..c484a17 100644
--- a/rng/mathml4.rng
+++ b/rng/mathml4.rng
@@ -1,18 +1,37 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<grammar xmlns="http://relaxng.org/ns/structure/1.0">
-  <!--
-    MathML 4 (full)
-    ##############
-  -->
-  <!--
-        Copyright 1998-2022 W3C (MIT, ERCIM, Keio)
-    
-        Use and distribution of this code are permitted under the terms
-        W3C Software Notice and License
-        http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
-  -->
+<!--
+  MathML 4 (full)
+  ##############
+-->
+<!--
+      Copyright 1998-2022 W3C (MIT, ERCIM, Keio)
+  
+      Use and distribution of this code are permitted under the terms
+      W3C Software Notice and License
+      http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
+-->
+<grammar ns="http://www.w3.org/1998/Math/MathML" xmlns="http://relaxng.org/ns/structure/1.0">
   <!-- Presentation MathML -->
-  <include href="mathml4-presentation.rng"/>
+  <include href="mathml4-presentation.rng">
+    <define name="anyElement">
+      <element>
+        <anyName>
+          <except>
+            <nsName/>
+          </except>
+        </anyName>
+        <zeroOrMore>
+          <choice>
+            <attribute>
+              <anyName/>
+            </attribute>
+            <text/>
+            <ref name="anyElement"/>
+          </choice>
+        </zeroOrMore>
+      </element>
+    </define>
+  </include>
   <!-- Content  MathML -->
   <include href="mathml4-content.rng"/>
 </grammar>
diff --git a/test/test-core-10.xml b/test/test-core-10.xml
new file mode 100644
index 0000000..54b6925
--- /dev/null
+++ b/test/test-core-10.xml
@@ -0,0 +1,3 @@
+<math xmlns="http://www.w3.org/1998/Math/MathML">
+<msup mathvariant="bold"><mn>1</mn><mi>x</mi></msup>
+</math>
diff --git a/test/test-full-10.xml b/test/test-full-10.xml
new file mode 100644
index 0000000..9b94359
--- /dev/null
+++ b/test/test-full-10.xml
@@ -0,0 +1,10 @@
+
+<math xml:lang="en" dir="rtl" xml:space="preserve" mathcolor="blue"  alignmentscope="true" xmlns="http://www.w3.org/1998/Math/MathML" >
+
+ <mfrac intent="divide($a,$b)">
+  <apply arg="a"><sin/><ci>x</ci></apply>
+  <apply arg="b"><cos/><ci>x</ci></apply>
+ </mfrac>
+
+ 
+</math>
diff --git a/test/test-legacy-09.xml b/test/test-legacy-09.xml
new file mode 100644
index 0000000..f3b9c3b
--- /dev/null
+++ b/test/test-legacy-09.xml
@@ -0,0 +1,21 @@
+<math xmlns="http://www.w3.org/1998/Math/MathML" >
+
+ <mfrac><mn>1</mn><malignmark/></mfrac>
+
+ <msup><mn>1</mn><malignmark/></msup>
+
+ <mn><malignmark/></mn>
+ 
+ <mtable groupalign="{left}">
+  <mtr groupalign="{left}">
+   <mtd groupalign="left"><mn>1</mn><maligngroup/><malignmark/></mtd>
+   <mtd groupalign="left"><mn>1</mn></mtd>
+  </mtr>
+ </mtable>
+
+ <mtable groupalign="{left right} {left right} ">
+</mtable>
+
+<mrow> <mi><mglyph/></mi> <malignmark/></mrow>
+ 
+ </math>
diff --git a/test/test-presentation-06.xml b/test/test-presentation-06.xml
index 74d7207..4f6c52b 100644
--- a/test/test-presentation-06.xml
+++ b/test/test-presentation-06.xml
@@ -42,8 +42,6 @@
 </mstack>
 
 
-<mtable groupalign="{left right} {left right} ">
-</mtable>
 <mfenced separators="||,">
 </mfenced>
 
diff --git a/test/test-presentation-08.xml b/test/test-presentation-08.xml
index c13f3e4..7f5f51a 100644
--- a/test/test-presentation-08.xml
+++ b/test/test-presentation-08.xml
@@ -1,3 +1,3 @@
 <math xmlns="http://www.w3.org/1998/Math/MathML">
-<mrow> <mi><mglyph/></mi> <malignmark/></mrow>
+<mrow> <mi><mglyph/></mi></mrow>
 </math>
diff --git a/test/test-presentation-15.xml b/test/test-presentation-15.xml
new file mode 100644
index 0000000..1caf050
--- /dev/null
+++ b/test/test-presentation-15.xml
@@ -0,0 +1,14 @@
+<math xmlns="http://www.w3.org/1998/Math/MathML" >
+
+ <mrow><mn>1</mn><malignmark/></mrow>
+
+ <mfenced><mn>1</mn><malignmark/></mfenced>
+
+ 
+ <mtable>
+  <mtr>
+   <mtd><mn>1</mn><maligngroup/><malignmark/></mtd>
+  </mtr>
+ </mtable>
+ 
+ </math>