The names of clades may be established through conversion of preexisting names or introduction of new names. A directly-specified-ancestor definition is a special case of the minimum-clade definition in which the ancestor in which the clade originated is specified directly rather than indirectly through its descendants. In order for a clade name to be established, the protologue must include a statement about the hypothesized composition of the clade. Clade names are generally to be selected in such a way as to minimize disruption of current and/or historical usage and to maximize continuity with existing literature. The creation of new clade names that add such a prefix to a preexisting or converted name with a rank-specific ending may lead to confusion for users of the rank-based system because the new name may be incorrectly taken to imply the existence of a genus name with the same prefix.