What does the error "The element cannot contain white space. Content model is empty." mean?

Question

I'm putting together an xml schema for a simple xml (see bellow for both xml and schema). But I keep getting the following error with regards to the section node: "The element cannot contain white space. Content model is empty." . Browsing the net I could not find any concise explanation as to what it means so I can fix it. Can anyone help?

Edit: thanks for all for offering help with the schema. I think it would help to have a concise description of what content model is and why it is empty here.

XML:

<config>
   <section name="facets">
      <facet type="format" label="Format" max="4"/>
      <facet type="language" max="4"/>
      <facet type="pubdate" max="6" submax="8"/> 
      <facet type="ice_topic" label="Fiction: Topic"/>
   </section>
</config>

Schema:

<?xml version="1.0" encoding="utf-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
   <xs:element name="config">
      <xs:complexType>
         <xs:sequence>
            <xs:element name="section" type="sectionBase"/>
         </xs:sequence>
      </xs:complexType>
   </xs:element>
   <xs:complexType name="sectionBase">
      <xs:attribute name="name" type="xs:ID"/>
   </xs:complexType>


   <xs:complexType name="sectionFacets" >
      <xs:complexContent>
         <xs:extension base="sectionBase">
            <xs:sequence>
               <xs:element name="facet" type="sectionFacetsBaseFacet"/>
            </xs:sequence>
         </xs:extension>
      </xs:complexContent>
   </xs:complexType>
   <xs:complexType name="sectionFacetsBaseFacet">
      <xs:attribute name="label" type="xs:ID"/>
      <xs:attribute name="max" type="xs:positiveInteger"/>
   </xs:complexType>
   <xs:complexType name="sectionFacetsFormat">
      <xs:complexContent>
         <xs:extension base="sectionFacetsBaseFacet"/>
      </xs:complexContent>
   </xs:complexType>
   <xs:complexType name="sectionFacetsPubdate">
      <xs:complexContent>
         <xs:extension base="sectionFacetsBaseFacet">
            <xs:attribute name="submax" type="xs:positiveInteger"/>
         </xs:extension>
      </xs:complexContent>

   </xs:complexType>
</xs:schema>

Answer 1

The label attribute of facet is set to xs:ID and this doesn't allow spaces. You might want to use xs:string instead.

Answer 2

There are several problem in our schema as others have already mentioned. Try something like this:

The extensible schema:

<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <!-- never used; just to be extended -->
    <xs:complexType name="sectionBaseType" abstract="true">
        <xs:attribute name="name" type="xs:ID"/>
    </xs:complexType>

    <!-- extension of the sectionBaseType -->
    <xs:complexType name="sectionSpecialized">
        <xs:complexContent>
            <xs:extension base="sectionBaseType">
                <xs:sequence>
                    <xs:element name="facet" type="leftToTheReaderType"
                        maxOccurs="unbounded"/>
                </xs:sequence>
            </xs:extension>
        </xs:complexContent>
    </xs:complexType>

    <!-- config may contain a single section or one of its extensions -->
    <xs:complexType name="configType">
        <xs:sequence>
            <xs:element name="section" type="sectionBaseType"/>
        </xs:sequence>
    </xs:complexType>

    <!-- a single root node called "config" -->
    <xs:element name="config" type="configType"/>
</xs:schema>

How to use the schema:

<?xml version="1.0" encoding="UTF-8"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <!-- note the xsi:type to specify the actual type of the section!! -->
    <section name="facets"
        xsi:type="sectionSpecialized">
        <facet .../>
        <facet .../>
        <facet .../> 
        <facet .../>
    </section>
</config>