I was surprised to see that this page is titled Powertype (UML) rather than simply Powertype. This would be OK if there were another page titled Powertype (XXX), but there isn't. Powertypes are not a UML construct, are not exclusive of UML and, in fact, were defined before their inclusion as part of UML (see J. J. Odell (1994). "Power types". Journal of Object-Oriented Programming, 7(2): 8-12). For this reason, I strongly suggest that this page should (a) address powertypes as the theoretical construct that they are, (b) include a section of how powertypes are implemented in UML, and (c) change its title to simply Powertype.