Correct orientation of thermostat.

Car is a Skoda Favorit 94 Glxie.

Haynes manual says to have the arrow pointing up, which from the unclear pictures looks like it means it should be pointing vertically up to the sky.

Have been told by someone that the arrow should point in the direction of water flow, hence horizontally toward the top radiator hose. This however puts the jiggle pin at the bottom, and my understanding is this should be at the top to help remove air from the thermostat housing.

What's the usual convention?

Thanks in advance.