As promised, here are the exploded photo's of the drinking cap.
You can see the cap in the "closed" position with all orifices covered.
When it's in the drinking position, you can see the alignment of the small hole at"12 o'clock". The air entrainment through this hole is what gives it the smooth controlled flow form the bottle.
The formed drinking "spout" at "6 o'clock" is short enough without clattering your teeth whilst on the move.
The last photo shows the cap in two pieces ready for cleaning. There's no chance of foreign matter being inaccessible.
I hope this post wasn't too laborious for you all, but when one finds a product that works, it's beneficial to broadcast it for the opinions of others doing the same research.
Slange