Tourney: Cambridge Indoor Open – 26/27th February

Cambridge, I just read the rules, can you clarify something for me:

How are you defining possession in this case? Is it enough for the ball to touch a defensive players mallet in any form? Do they have to have possession for a certain amount of time? Does the offensive team have to back off?

What I'm asking is what the offensive team are obliged to do in that situation.

I guess the offensive team would have to at least retreat from the defender's d, if not to their own half.

Cambridge?