A response to http://stackoverflow.com/questions/18562720/validating-a-nested-xml-element-with-an-empty-namespace-using-xsd

GroupProj2.xsd

<?xml version="1.0" encoding="utf-16"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://schemas.microsoft.com/developer/msbuild/2003" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:import schemaLocation=".\GroupProjInc.xsd" />
  <xs:element name="Project">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="PropertyGroup">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="ProjectGuid" type="xs:string" />
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element maxOccurs="unbounded" name="ItemGroup">
          <xs:complexType>
            <xs:sequence minOccurs="0">
              <xs:element maxOccurs="unbounded" name="Projects">
                <xs:complexType>
                  <xs:attribute name="Include" type="xs:string" use="required" />
                </xs:complexType>
              </xs:element>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element name="ProjectExtensions">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="Borland.Personality" type="xs:string" />
              <xs:element name="Borland.ProjectType" />
              <xs:element name="BorlandProject">
                <xs:complexType>
                  <xs:sequence>
                    <xs:element ref="BorlandProject" />
                  </xs:sequence>
                </xs:complexType>
              </xs:element>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element maxOccurs="unbounded" name="Target">
          <xs:complexType>
            <xs:sequence>
              <xs:element minOccurs="0" name="CallTarget">
                <xs:complexType>
                  <xs:attribute name="Targets" type="xs:string" use="required" />
                </xs:complexType>
              </xs:element>
              <xs:element minOccurs="0" name="MSBuild">
                <xs:complexType>
                  <xs:attribute name="Projects" type="xs:string" use="required" />
                  <xs:attribute name="Targets" type="xs:string" use="required" />
                </xs:complexType>
              </xs:element>
            </xs:sequence>
            <xs:attribute name="Name" type="xs:string" use="required" />
          </xs:complexType>
        </xs:element>
        <xs:element name="Import">
          <xs:complexType>
            <xs:attribute name="Condition" type="xs:string" use="required" />
            <xs:attribute name="Project" type="xs:string" use="required" />
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>