It's matching the shape of the tarp to the shape of the hammock that he is talking about. The hammock has pullouts at your left shoulder and right knee and the tarp should be set up that way too... if you don't pay attention you might end up with your tarp set up to cover your hammock as if the pullouts where at your right shoulder and left knee and you will not like what happens if it rains.
Originally Posted by CajunHiker
I don't think the shiny side up or down matters.
Yep, that is what I meant. If you see that hammock pull out is not matched by the tarp shape- so that the right knee and left shoulder hammock pull outs are well covered by the tarp, just flip it over. You don't even have to disconnect it if in a hurry, just leave it attached to the prussicks/suspension and flip it upside down. You will then notice a big dif in lateral coverage.