Mr. WK. Thank you for the clarification. A fastening that can be slipped or immediately adjusted as the level changes is what I was attempting to describe. NEVER any knots or hard cleating.
I still advise a back-up to hand holding.
I suspect my poor advice is due to number of lockages we've done in the past 30+ years (I estimate 1000+). I "assumed" one would know the drill.