Oh really? I didn't know! When I was in the US I only got told to make sure the flag didn't touch the ground when I put it out on the house or took it down in the evening. But that's it.

Sweden don't have codes like that. Not many at least. If you have a flagpole with a flag on it, take the flag down at sundown. And don't burn the flag. That's it, I think. :-)