||Holds a composite CP that holds either choice lists of
content particles, or sequence lists of content particles.
||The ContentModel specifies a ContentSpec
where the element contains only child elements.
||Class to hold the content specification
specified for an Element in the element
||From the XML Specifications
[Definition: An element type has mixed content
when elements of that type may contain character
data, optionally interspersed with child elements.]
In this case, the types of the child elements may
be constrained, but not their order or their
number of occurrences.
||This class holds the ContentParticle that contains
an Element Name followed by the Multiplicity.