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GBBopen also allows a link-pointer object to be used as an outgoing link pointer. An application developer can define a link-pointer object to hold attributes (such as “confidence” or “applicability conditions”) that are associated with the outgoing pointer.
Attributes of a link relationship that are not directional (attributes that are to be the same when obtained from either side of the link), are best represented by representing the “link” as a first-class unit instance rather than by maintaining a link-pointer object on each end of the link that have consistent values.
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