Synopsis:

"p5" (indicating whether or not RETURN protocol variable is true) only appears on tracking phase charts, but the description of RETURN variable's definition in 8.2.2 regarding tracking/processing phases implies that nothing should be on a tracking phase chart unless it requires a RETURN value of true. This appears to be a redundancy.

Response:

Predicate "p5" has the meaning: "returns TRUE if RETURN protocol variable is TRUE"

The State Tables for the Tracking Phases cover states and events that can relate to copy/non-returnable items as well as returnable items. Examples are of tracking phase states that relate to copy/non-returnable items include RECEIVED, DAMAGED, LOST states (and related APDUs) as well as the message and status-query APDUs.

e.g., a shipped photocopy could be lost/damaged in the mail

This means that there are entries in the tracking phase state-tables to which the RETURN protocol variable = false can also be appropriate.

Therefore, predicate p5 is not redundant

Note: p5 appears only in the columns for RECEIVED state in the Responder State table and SHIPPED state in the Requester State Table, and only appears in those cells for states for which a transaction for a non-returnable item is also applicable.

"p5" prevents the transaction for the non-returnable item from moving to states in which only transactions for returnable items can exist.

I.e., the "p5" predicate applies only to the following incoming events for the Requester in a RECEIVED state:

in a SHIPPED state:

And the following incoming events for the Responder in a SHIPPED state: