East Asian esoteric Buddhism works with a set of five elements, earth, water, fire, wind and space, and assigns to each a Siddham syllable: a, va, ra, ha and kha in that order. The set is compact, memorable and endlessly reproducible, and it is the single most visible use of the script in Japan.
Its standard form is the gorinto, a stone pagoda of five stacked shapes, a cube at the bottom, then a sphere, a pyramid, a half-moon and a jewel-shaped finial, each shape belonging to one element and each carrying that element's syllable. The same scheme is cut into wooden grave tablets, drawn on ritual objects and used in the layout of images. Once the sequence is known the monument reads at a glance, from the ground upward, earth to space.
Two things about the set are worth noticing. It is a set of five syllables and not a set of five letters: each is a Siddham character, and the whole is a scheme in which written sign, element, shape and position in a stack all correspond. And it is a scheme the atlas can describe from the outside, because the monuments are public and their reading is documented, while the practices the syllables belong to inside the two Japanese esoteric schools are transmitted under initiation and are not the atlas to set out. What is on the stone is a fact about the stone. What is done with it is not the atlas to say.