Inheritance and References
Function
The "reference" system (see
"References") relies on the addition of an
ID attribute for each referenced tag, and
IDREF/
IDREFS attributes for the referencing tags.
When a tag is referenced from a class using inheritance, the ID attribute is propagated to the inherited elements.
The values of the parameters defining how the attribute is generated are also propagated.
Example
This case uses the "Paperback" class, which inherits the "Book" class. The attribute identifying the "Book" class is called ISBN. The "Paperback" class inheriting the "Book" class will inherit the "ISBN" attribute.
The attribute identifying the "Paperback" class is automatically set to this value.
Thus the XDD Compulsory ID Attribute, XDD ID Attribute Name and XDD ID Attribute Required parameters are set to the values of the inherited class.
The class that references "Book" will also reference "Paperback".
Of course, it is possible to overload any of these parameters locally.
Result
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Diagram
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XML Document
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<Paperback Name="ForWhomTheBellTolls" ISBN="123-456-789"/>
<Book Name="A Book " ISBN="789-456-123"/>
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