> 16-XX Associative rings and algebras > 16UXX Conditions on elements

16U10 Integral domains	16U20 Ore rings, multiplicative sets, Ore localization	16U30 Divisibility, noncommutative UFDs
16U60 Units, groups of units	16U70 Center, normalizer (invariant elements)	16U80 Generalizations of commutativity
16U99 None of the above, but in this section

16UXX Conditions on elements