City Of Heroes/Enhancements
Enhancements are added to existing powers, making them more powerful. There are several different types of enhancements, but only three real ranks to them (with a few exceptions, i.e. Hamidon Enhancements). They come in Training (TO) (useable by any hero), Dual Origin (DO) (usable by heroes of two different origins, i.e. Science and Technology), and Single Origin (SO) (usable only by heroes of one specific origin).