The prefixes that occur on a verb are added in specified order according to prefix type. This type of morphology is called a "position class template" (or "slot-and-filler template"). Below is a table of a recent proposal of the Navajo verb template (Young & Morgan 1987). Edward Sapir and Harry Hoijer were the first to propose an analysis of this type. A given verb will not have a prefix for every position, in fact most Navajo verbs are not as complex as the template would seem to suggest.