How to restrict max children for a node containing different node types

Question

Hi,
I have the following XML:
<categories>
    <category id="hsp">
        <cardUsage id="hsp.approvals">
            <tabUsage id="hsp.approvals.puListing"/>
            <tabUsage id="hsp.approvals.puDashboard"/>
        </cardUsage>
        <cardClusterUsage id="hsp.someCluster">
            <cardUsage id="hsp.someCluster.approvals"/>
        </cardClusterUsage>
    </category>
    <category  id="psb">
    </category>
    <category  id="pfp">
    </category>
    <category  id="cx">
    </category>
</categories>
I need to put a restriction that node category cannot have more than 16 children (cardUsage nodes + cardClusterUsage nodes).
The way I was thinking to achieve this is, use a new node Usage as child of category. I could set maxOccurs on Usage to 16. And then in Usage use the xs:choice to choose between cardUsage and cardClusterUsage. And setting the maxOccurs to 1.
Please let me know if there is a better way to do this. Or you see any flaws in my proposal.
Thanks for you time in advance,
Manish.

Answer 1

Does the order of category children matter?
If not, you can directly set maxOccurs to 16 in the xs:choice element :
<xs:element name="category">
  <xs:complexType>
    <xs:choice maxOccurs="16">
      <xs:element name="cardUsage" type="..."/>
      <xs:element name="cardClusterUsage" type="..."/>
    </xs:choice>
    <xs:attribute name="id" type="string"/>
  </xs:complexType>
</xs:element>