rotation question

how do you make a prim flip up 90 degrees without caring where on the z axis the item is turned?
its not jumping out at me the way it is if x and y can have different meanings depending on the z.

Not entirely sure what you're asking....but you can either position an object or rotate it in edit....the axis points always remain the same on the prim...anotherwords when you create a prim....it's xyz coorrdinates will always reflect that original position as upright.....when you rotate it....it's center point will always be the same, no matter what how you alter the prim.
Usually is's easiest to start out with prims that line up with the grid itself so when you're moving or rotating the have a squared view of the xyz points. If that makes sense. lol

I don't know if I answered your question at all.....but rotation happens only in 'rotate' in edit....there's no other way to flip a prim, so to speak. You can either rotate with the red, green and blue wheels.....or enter the rotation degrees in the rotation boxes.

This might be a good question to put to the builder's forum in the content creation section.

For most uses, I'd think it wouldn't matter how SL did the rotational math, as long as your end result was the same (the prim facing the way you wanted it.) But obviously you have a special case in which it does matter, or you wouldn't be asking. So it sounds like a good question for Building Tips.