BPMN21 — Sub-Choreography is not a compound Activity

i) Chapter/Section 8.3.7. Page 87. Figure 8.22. According to classes and their relationships:
Both Activity and Choreography Activity are sub-classes of Flow Node.

ii) Chapter/Section 11.4.2. Page 338. It says:
“A Sub-Choreography is a compound Activity in that it has detail that is defined as a flow of other Activities, in this case, a Choreography.”

COMMENTS:

According to Choreography Activity is not a type of Activity, because there is not generalization from Choreography Activity to Activity.

Then, A Sub-Choreography cannot be a “compound Activity”, because a Sub-Choreography is not a type of Activity.

SUGGESTIONS:

In (ii) it should say:
“A Sub-Choreography is a compound ChoreographyActivity in that it has detail that is defined as a flow of other ChoreographyActivities.”

“Activity” should be replaced by “ChoreographyActivity”
“Activities” should be replaced by “ChoreographyActivities