A primitive method to return a data object that represents the data of the receiver in a given type.
A primitive method overridden by subclasses to return a data object that represents the data of the receiver in a given type (aType). The default implementation raises an NSInternalInconsistencyException. This method is invoked by the default implementation of fileWrapperRepresentationOfType:.
aType is the type name corresponding to the value of the CFBundleTypeName entry in the document type’s Info.plist dictionary.