Value: 4
If the document's schema is an XML Schema []
, this constant represents the if simple types are involved.
The reference type definition is derived by union from the other
type definition if there exists two type definitions T1 and T2 such
as the reference type definition is derived from T1 by
DERIVATION_RESTRICTION or
DERIVATION_EXTENSION, T2 is derived from the other type
definition by DERIVATION_RESTRICTION, T1 has {variety} union, and one of the {member type definitions} is T2. Note that T1 could be
the same as the reference type definition, and T2 could be the same
as the other type definition.