XSD any elements in any order

Question

Hi,
I'm trying to figure out how to create an element that permits any number of certain elements to occur in any order, and I seem to be quite stuck. For example, given the special elements foo, bar, and foobar, I'd like to be able to create an XSD definition for the following:
<root>
<foo/>
<bar/>
<bar/>
<foo/>
<foobar/>
<bar/>
<foobar/>
<bar/>
<foo/>
</root>
Any ideas? I can do this:
<xsd:element name="root">
<xsd:complexType>
<xsd:sequence>
<xsd:choice minOccurs="0">
<xsd:element name="foo" type="FooType">
<xsd:element name="bar" type="BarType">
<xsd:element name="foobar" type="FooBarType">
</xsd:choice>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
But this seems not to work quite as expected. It lets me create:
<root><foo/></root>, <root><bar/></root>, or <root><foobar/></root>
But it doesn't permit having multiple occurrences of <foo> or even an occurrence of <foo> and one of <bar>.
Thanks

Answer 1

This seems to work for me<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<xsd:element name="root">
  <xsd:complexType>
    <xsd:sequence>
      <xsd:element ref="foobarelements" maxOccurs="unbounded"/>
    </xsd:sequence>
  </xsd:complexType>
</xsd:element>
<xsd:element name="foo" type="xsd:anyType"  substitutionGroup="foobarelements"/>
<xsd:element name="bar" type="xsd:anyType"  substitutionGroup="foobarelements"/>
<xsd:element name="foobar" type="xsd:anyType"  substitutionGroup="foobarelements"/>
<xsd:element name="foobarelements" type="xsd:anyType"/>
</xsd:schema>