Defines the different constraints on an attribute's presence on an element.

Defines the different possible attribute types.

Where nested subelements cannot occur within an element, its contents can be declared to consist of one of the types of declared content contained in this enumeration.

The type of the content model group, defining the order in which child elements can occur.

Qualifies the occurrence of a child element within a content model group.

Specifies how white space is handled. (Not defined in PORTABLE framework, so we added it here).