5.5 http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac Schema

 <xsd:schema targetNamespace="http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac" elementFormDefault="qualified" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" xmlns="http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac">
   <xsd:import namespace="http://schemas.openxmlformats.org/officeDocument/2006/relationships" schemaLocation="orel.xsd"/>
   <xsd:import namespace="http://schemas.openxmlformats.org/spreadsheetml/2006/main" schemaLocation="xlbasictypes.xsd"/>
   <xsd:attribute name="dyDescent" type="xsd:double"/>
   <xsd:attribute name="knownFonts" type="xsd:boolean"/>
 </xsd:schema>