Type the three-lane swim-lane for the BorrowBox return flow. The vertical bars are lane boundaries; every step that crosses one is a hand-off.

Answer

Member | Locker Controller | Librarian ------------------+----------------------+------------------ 1 drop tool in | | a free locker | 2 read tag, lock | | 3 flag for inspect | | | 4 inspect + grade | | 5 re-shelve OR | | raise damage

Producing the partition is the skill; reading one is not. Notice what typing it exposes: three lane crossings, and every one of them is a place where responsibility changes hands and the flow can stall. An activity diagram of the same return shows the same five actions and hides all three hand-offs, which is the whole reason the swim-lane variant exists.

Pressman 9e ch8 §8.4.1, §8.5.3