5.18 http://schemas.microsoft.com/office/spreadsheetml/2016/revision5 Schema

 <xsd:schema targetNamespace="http://schemas.microsoft.com/office/spreadsheetml/2016/revision5" elementFormDefault="qualified" xmlns="http://schemas.microsoft.com/office/spreadsheetml/2016/revision5" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:x="http://schemas.openxmlformats.org/spreadsheetml/2006/main">
   <xsd:import namespace="http://schemas.openxmlformats.org/spreadsheetml/2006/main" schemaLocation="xlstyles.xsd"/>
 </xsd:schema>