Accompa allows you to assign 5 different types of relationships.

1. Includes
2. Is Included By
3. Extends
4. Is Extended By
5. Supersedes
6. Is Superseded By
7. Is Related To

These relationships are mutually exclusive -- i.e. two given use cases may have only one relationship between them.

#1 and #2 above are inverse of each other - and should be used when one use case includes another use case.

Similarly, #3 and #4 are inverse of each other - these should be used when one use case extends another.

Similarly, #5 and #6 are inverse of each other - these should be used when one use case has superseded another, or when there are duplicate use cases.

Use #7 when two use cases are related, but the relationship does not fall under one of the other 6 types.