}else{node=AMcreateMmlNode((underover?"mover":"msup"),node);node.appendChild(result[0]);}
  node=AMcreateMmlNode("mrow",node);}else{node=AMcreateMmlNode(symbol.tag,node);if(symbol.input=="\\atop"||symbol.input=="\\choose")
  node.setAttribute("linethickness","0ex");node.appendChild(result[0]);if(symbol.input=="\\choose")
  node=AMcreateMmlNode("mfenced",node);}}
  return[node,str,tag];}
  function AMparseExpr(str,rightbracket,matrix){var symbol,node,result,i,tag,newFrag=document.createDocumentFragment();do{