“ In the context of a work of fiction, the term canon denotes the material accepted as "official" in a fictional universe's fan base. It is often contrasted with, or used as the basis for, works of fan fiction, which are not considered canonical. It is used in two slightly different meanings: first, "it refers to the overall set of storylines, premises, settings, and characters offered by the source media text" ”
Some writers define at the start of their work of fan fiction which source material they are relying on. This is because of variations between the manga and the anime. For example, the female version of Ranma is presented with black hair in the manga and red hair in the anime.