Regestoy (regestO), or "the Art", is the D'ni discipline of writing Descriptive Books or Linking Books. The word itself is a combination of the definite article prefix "the" (reh, re) and the D'ni word for "art" (gestoy/gehstoy, gestO).
Described as both an art and "the science of precise description", an author uses regestoy to describe a physical place, like an island on a planet, in exacting and comprehensive detail. This is a skill which took many years of practice to hone, and even more to master. A completed Book enables its user to physically travel to the place described within its pages. Underlying regestoy was the foundational belief that writers were not creating new worlds, but merely linking to places that existed in parallel universes. The D'ni called these parallel universes Ages (sevtee, sevtE).
Regestoy was made possible through specially-formulated ink and paper—which was bound together in a hard leatherbound volume—and a special written dialect called gahro hevtee (garo hevtE)—literally, "great words"—which allowed writers to express extremely complex ideas in a compact space. Blank Books, called kortee'nea (KortE'nEa), were carefully guarded by the Guild of Writers, as were the formulae that described the manufacture of their individual components. While access to the practice of Age writing was primarily the province of the Writers' Guild, others are known to have learned it as well.