how to specify external schema in processContents=lax
<xs:element name="detail">
    <xs:annotation>
        <xs:documentation>
        </xs:documentation>
    </xs:annotation>

    <xs:complexType>
        <xs:sequence>
            <xs:any processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:anyAttribute processContents="skip"/>
    </xs:complexType>
</xs:element>

<detail>
   <drawing>
      <name="test"/>
    </drawing>
</detail>

<detail>
   <icon>
      <icon_name="testIcon"/>
      <icon_image="iconImage.jpg"/>
    </icon>
</detail>