Samsung Tab A7 Lite Model Number Suffix Meaning

What do the suffix numbers on Samsung Tablets (and possibly phones) mean. I ask because I work at a prepaid cell phone retailer. We carry the Galaxy Tab A7 Lite. The model number is SM-T227U. I had seen something on a forum on a page about a cell phone model where it was said that the "U" stands for unrootable. When I search for details about rooting the T227U I get pages talking about the "T227" saying it is indeed rootable. Does the U stand for unrootable? Is the T227U rootable? What exactly do the suffix letters on a Samsung tablet indicate?