Concepts are divided into forty main "Genera", each of which gives the first, two-letter syllable of the word; a Genus is divided into "Differences", each of which adds another letter; and Differences are divided into "Species", which add a fourth letter. For instance, "Zi" identifies the Genus of "beasts" (mammals); "Zit" gives the Difference of "rapacious beasts of the dog kind"; "Zitα" gives the Species of dogs. (Sometimes the first letter indicates a supercategory—e.g. Z always indicates an animal—but this does not always hold.) The resulting Character, and its vocalization, for a given concept thus captures, to some extent, the concept's semantics.