A more thorough explanation:

ACTIONES LEGIS

Actiones legis were legal actions in ancient Rome that were used to resolve disputes. These actions were brought before a magistrate and were based on well-established forms.

Actiones nominatae were a type of actiones legis that were named actions. These actions were used in the Chancery and had well-established forms. An example of an actiones nominatae is casu consimili, which means "similar case." This was used when a similar case had already been decided and the decision could be applied to the current case.

For example, if a case had already been decided where a person was found guilty of stealing a horse, and a similar case came up where a person was accused of stealing a cow, the decision from the previous case could be applied to the current case using casu consimili.