In the Adding Optional Actions to a Case Type lesson there is an inconsistency regarding what an Optional User Action is which leads me to question which is the correct definition?
In the first part, the lesson states that on the completion of an optional user action, the user may or may not return to the primary path of the case.
Later on, it says: Optional user actions are single tasks and return to the primary path of the case, whereas an optional process is a series of steps that is not required to return to the primary path of the case.
the principle is that optional actions and processes do not or rather shall not change the progress/state of the case. So, after doing whatever optional task(s) you constructed, you return back to where you started the optional action/process. That's how it works in principle. But of course you are able to construct an optional action/process that backfires to the regular flow, either by jumping somewhere else (hence the "may not return") and opening additional follow-up assignments or cancelling an online order (with no order left to return to). Anyway, the "open assignment" you left before initiating the optional task, will be there waiting for you to continue, regardless if that would make sense after the optional task or not. I think there is a "kill" option for those if needed.