Behaviour in case of errors

[martinkrammer]

Section 3.3.6 Allowed PDUs per State
"may be sent" is considered optional, according to the specification annex. Hence, a DCP slave author may choose to send error codes or not.
Alternatively, a standard-compliant slave may choose to go to ERRORHANDLING state instead.

This behaviour is adverse for testing, because the implemented strategy is unknown.

1. Not allowed PDUs may be silently ignored.
2. Error codes may be sent alternatively.
3. Slave may proceed to ERRORHANDLING immediately and without reason.

This situation allows too much options. The question arises if this should be defined in a more narrow way.

[martinkrammer]

Proposal:
The initial design intention was that slaves should send error codes.

1. Change "may be sent" to "must be sent".
2. The master must be aware that a slave could always go to ERRORHANDLING.
   This is considered as non-braking behaviour, hence target a clarification version

[martinkrammer]

Add note (non-normative) to specification: "The master must be aware that a slave could always go to ERRORHANDLING."

Polled in web meeting.