Before revision: The only cable structure recognized by the official USB standards is one with an A plug and a B plug (such as Micro USB, Lightning, and USB-C among others)at either end .
After revision: The only cable structure recognized by the official USB standards is one with either a type A plug or a type C plug on one end, and either a type B plug or a type C plug on the other end (adapters with a type C plug and a type A or type B socket are also allowed, while adapters with a type C socket and a type A or type B plug or socket are explicitly not allowed) .