UML22 — Use case extension inconsistencies

According to Figure 401, an Extend object references at least one ExtensionPoint which itself must be owned by exactly one UseCase.
Therefore it seems that the Extend.extendedCase property is redundant and should be derived.

Also the section for ExtensionPoint does not include the useCase property shown in Figure 401, which itself does not show the

.

Proposed resolution
-----------------------------

1) Update Figure 401 to replace +extendedCase by +/extendedCase

2) Update Figure 401 to replace +useCase by +useCase

.

3) Section 16.3.3 Extend: update the Associations section to replace:
extendedCase : UseCase [1] References the use case that is being extended. (Specializes DirectedRelationship.target.)

by

/extendedCase : UseCase [1] References the use case that is being extended: this is derived as the Use case that owns the ExtensionPoint(s). (Specializes DirectedRelationship.target.) in OCL: extendedCase = self.extensionLocation->useCase

4) Section 16.3.4 ExtensionPoint update the Associations section to replace:
No additional associations

by

useCase: UseCase [1] References the use case that owns the ExtensionPoint. (subsets owner.)

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