Irosun is the four-mouth sign of the Diloggun throw. Its reading, like that of every parent Odu in this set, takes place within a specific institutional structure that developed in Cuba over roughly two centuries: the casa de santo, a religious house headed by an initiated elder, usually called a padrino or madrina, godfather or godmother, who trains younger initiates in the liturgy, the songs and the divinatory corpus of their tradition.
An oriate, a senior specialist in ritual protocol and in reading the shells and the coconut oracle called Obi, typically presides over the more elaborate ceremonies at which Diloggun is cast. This is markedly different from Ifa's structure, in which authority to divine rests on initiation specifically to Orunmila as a babalawo, a title and process historically closed to women in most Lucumi lineages, a restriction Diloggun as a whole does not share since its priesthood spans both sexes. Irosun's own content, the proverbs and prescribed works recorded against it in the oral corpus, belongs to that initiatory structure and to the person receiving a reading, and is not part of what a public reference can responsibly set out. What can be stated is the shape of the institution that holds it, and the fact, recorded by Bascom, that Irosun's name is one of the majority shared with Ifa's corresponding parent figure.