I don't think it really matters. If you have the back sticking up, the ports are exposed... but that doesn't really matter because it's going to be closed. If you have the front side up, little tiny particles could get trapped in your lid with no way to get out!... but again... its closed. I don't think it matters.
JW, what do you really think? Telling someone to use "Common Sense" is everything but productive kthx.