Saxon test open042x.xsd has:

<xs:openContent>
     <xs:any namespace="##other" processContents="lax" maxOccurs="unbounded"/>
</xs:openContent>

But according to the Appendix A [1], <xs:any> under <xs:openContent> can't specify min/maxOccurs attributes.

(With irrelevant items omitted)

  <xs:element name="openContent" id="openContent">
          <xs:sequence>
            <xs:element name="any" minOccurs="0" type="xs:wildcard"/>
          </xs:sequence>
  </xs:element>

  <xs:complexType name="wildcard">
      <xs:extension base="xs:annotated">
         <xs:attributeGroup ref="xs:anyAttrGroup"/>
      </xs:extension>
  </xs:complexType>

where "xs:anyAttrGroup" doesn't allow min/maxOccurs attributes. These attributes are included in the "xs:occurs" group, which is referenced by the normal <any> element:

  <xs:element name="any" id="any">
        <xs:extension base="xs:wildcard">
          <xs:attributeGroup ref="xs:occurs"/>
        </xs:extension>
  </xs:element>

[1] http://www.w3.org/TR/xmlschema11-1/#normative-schemaSchema