title: Middle way between XSD all and XSD sequence
body: <p>I'm defining a user element with XSD. For this example, a user has a name, email and one or more nationalities. I've tried:</p>
  
  <pre><code>&lt;xs:all&gt;
    &lt;xs:element name="name" blabla /&gt;
    &lt;xs:element name="email" blabla /&gt;
    &lt;xs:element name="nationality" minOccurs="1" maxOccurs="unbounded" /&gt;
  &lt;/xs:all&gt;
  </code></pre>
  
  <p>However, that is illegal. Apparently elements inside an "All" can only occur one time (or not at all).
  I could fix this by changing the All to a Sequence, but then people would have to enter the properties in the exact order, which I actually don't care about.</p>
  
  <p>Is there a combination of these two available? Not according to <a href="http://www.w3schools.com/Schema/schema_complex_indicators.asp" rel="noreferrer">http://www.w3schools.com/Schema/schema_complex_indicators.asp</a>, but maybe it's hidden (or my inexperienced eyes don't see it).</p>
  
  <p>By intuition, I also tried:</p>
  
  <pre><code>&lt;xs:all&gt;
    &lt;xs:element name="name" blabla /&gt;
    &lt;xs:element name="email" blabla /&gt;
    &lt;xs:sequence&gt;
      &lt;xs:element name="nationality" minOccurs="1" maxOccurs="unbounded" /&gt;
    &lt;/xs:sequence&gt;
  &lt;/xs:all&gt;
  </code></pre>
  
  <p>But that's unfortunately invalid.</p>
  
  <hr>
  
  <p>Here is the current, real, piece of XSD:</p>
  
  <pre><code>  &lt;!-- user --&gt;
    &lt;xs:complexType name="user"&gt;
      &lt;xs:sequence&gt;
        &lt;xs:element name="firstname" type="xs:string" minOccurs="1" maxOccurs="1" /&gt;
        &lt;xs:element name="appendix" type="xs:string" minOccurs="0" maxOccurs="1" /&gt;
        &lt;xs:element name="lastname" type="xs:string" minOccurs="1" maxOccurs="1" /&gt;
        &lt;xs:element name="address" type="xs:string" minOccurs="1" maxOccurs="1" /&gt;
        &lt;xs:element name="zipcode" type="xs:string" minOccurs="1" maxOccurs="1" /&gt;
        &lt;xs:element name="city" type="xs:string" minOccurs="1" maxOccurs="1"/&gt;
        &lt;xs:element name="username" type="xs:string" minOccurs="1" maxOccurs="1"/&gt;
        &lt;xs:element name="email" type="xs:string" minOccurs="1" maxOccurs="1"/&gt;
        &lt;xs:element name="country" type="country" minOccurs="1" maxOccurs="1"/&gt;
        &lt;xs:element name="nationality" type="xs:string" minOccurs="1" maxOccurs="unbounded"/&gt;
      &lt;/xs:sequence&gt;
    &lt;/xs:complexType&gt;
  </code></pre>