"Both client and server SHOULD keep a connection for the duration of a sequence of operations. The client and server MUST include this header for the last operation in such a sequence. "
How do you implement this absolute requirement of the specification?
Consider the (presumably common) case in which the IPP client is interactively operated by a human user. When the user initiates the last operation in a sequence, how does the client predict that the user will be finished operating after the current operation?