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A new VALUE_CLUSTER, inheriting from ELEMENT and CLUSTER provides the semantics of both: a node which can itself have a value (like an ELEMENT), but may still hvae substructure. By inheriting from both CLUSTER and ELEMENT, it means that where either of these two are currently specified in the RM or archetypes, VALUE_CLUSTER could be substituted at runtime.The downside of this model is that there is no way to force a node to be just an ELEMENT or CLUSTER, since the new type is always substitutable.
Diagram
Impact Analysis
Candidate B - Remove ITEM_STRUCTURE
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- Removed ITEM_STRUCTURE and children.
- Added attribute structure_type:CODE_PRHASE to CLUSTER (as in 13606 model)
- Added method is_root() to ITEM
- ITEM inherits from DATA_STRUCTURE
- Added backguards relationship "parent" from ITEM to CLUSTER
Diagram
I have the source of this diagram if anyone wants it, it's a .dia file (http://live.gnome.org/Dia)
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