How to allow one element or another choice of elements in XSD?

Suppose that I have a <scene> element which can contain the following elements:

<episode> and/or <season>
OR <part>

Some examples:

<scene>
  <part></part>
</scene>

Another example:

<scene>
 <episode></episode>
 <episode></episode>
 <season></season>
 </scene>

Another one:

<scene>
 <episode></episode>
 <season></season>
 <episode></episode>
 </scene>

So the idea here is allowing episodes and seasons in <scene> (with unbounded limits). And if these two elements (seasons and episodes) doesn't exist you can use <part> element inside <scene> with unbounded limits.

I'm trying to do this in XML Schema. I tried groups and complexContent without success. Any ideas?

Solution

Use compound xs:choice elements:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xs:element name="scene">
    <xs:complexType>
      <xs:choice>
        <xs:element name="part" maxOccurs="unbounded"/>
        <xs:choice maxOccurs="unbounded">
          <xs:element name="episode"/>
          <xs:element name="season"/>
        </xs:choice>
      </xs:choice>
    </xs:complexType>
  </xs:element>

</xs:schema>

This says that scene can consist of either an unbounded number of part elements or an unbounded mix of episode and season elements.