Hi there,

we recently tripped validating qti documents with xmlint because it seems unable to validate the xinclude schema.

Here's the reduction I've come up with:

% wget http://www.w3.org/2001/XInclude.xsd
% xmllint --schema XInclude.xsd XInclude.xsd                                                           
XInclude.xsd:15: element complexType: Schemas parser error : complex type 'includeType': The content model is not determinist.
XInclude.xsd:40: element complexType: Schemas parser error : complex type 'fallbackType': The content model is not determinist.
WXS schema XInclude.xsd failed to compile
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xi="http://www.w3.org/2001/XInclude" targetNamespace="http://www.w3.org/2001/XInclude" finalDefault="extension">
  <xs:annotation>
   <xs:documentation>
    Not normative, but may be useful.
    See the REC http://www.w3.org/TR/XInclude for definitive
    information about this namespace.
   </xs:documentation>
  </xs:annotation>

  <xs:element name="include" type="xi:includeType"/>

  <xs:complexType name="includeType" mixed="true">
    <xs:choice minOccurs="0" maxOccurs="unbounded">
      <xs:element ref="xi:fallback"/>
      <xs:any namespace="##other" processContents="lax"/>
      <xs:any namespace="##local" processContents="lax"/>
    </xs:choice>
    <xs:attribute name="href" use="optional" type="xs:anyURI"/>
    <xs:attribute name="parse" use="optional" default="xml" type="xi:parseType"/>
    <xs:attribute name="xpointer" use="optional" type="xs:string"/>
    <xs:attribute name="encoding" use="optional" type="xs:string"/>
    <xs:attribute name="accept" use="optional" type="xs:string"/>
    <xs:attribute name="accept-language" use="optional" type="xs:string"/>
    <xs:anyAttribute namespace="##other" processContents="lax"/>
  </xs:complexType>

  <xs:simpleType name="parseType">
    <xs:restriction base="xs:token">
      <xs:enumeration value="xml"/>
      <xs:enumeration value="text"/>
    </xs:restriction>
  </xs:simpleType>
  
  <xs:element name="fallback" type="xi:fallbackType"/>

  <xs:complexType name="fallbackType" mixed="true">
    <xs:choice minOccurs="0" maxOccurs="unbounded">
      <xs:element ref="xi:include"/>
      <xs:any namespace="##other" processContents="lax"/>
      <xs:any namespace="##local" processContents="lax"/>
    </xs:choice>
    <xs:anyAttribute namespace="##other" processContents="lax"/>
  </xs:complexType>

</xs:schema>

% xmllint --version
xmllint: using libxml version 20708
   compiled with: Threads Tree Output Push Reader Patterns Writer SAXv1 FTP HTTP DTDValid HTML Legacy C14N Catalog XPath XPointer XInclude ISO8859X Unicode Regexps Automata Expr Schemas Schematron Modules Debug Zlib 

This seems like an error in libxml2 that makes it unable to parse that schema. Is that right? If not, how can I validate files with the qti schema that includes the xinclude schema? The schema that tripped us up is this <http://www.imsglobal.org/xsd/qti/qtiv2p1/imsqti_v2p1.xsd>

Do you need any more information?