Re: am I understanding this correctly?

 > do I understand this correctly?

Yes, but why not change it to:

    <xs:complexType name="groupingAndChildrenNodes">
      <xs:choice maxOccurs="unbounded" minOccurs="0">
        <xs:element ref="Anchor"/>
        <xs:element ref="Background"/>
        [...]
      </xs:choice>
    </xs:complexType>

In DTD, your existing model is ((Anchor | Background))* but with the 
above change it would be (Anchor | Background)* which has one less step 
of indirection.

Cheers,
Jeff Rafter