I'm sure there is some kind of guidance from the ICAO, but in my experience it's not always a given that the controllers are familiar with such guidance (or care about it). At the end of the day, all procedures (like all politics) are ultimately local. Which is why it's cheaper and easier to just ask the controller. If he decides to try to violate you, an obscure ICAO document won't be nearly as effective a defense as a taped conversation.
Don't you agree, Captain?