The arts of the bedchamber were classified in China as a branch of medicine, not of ethics and not of religion in the narrow sense. They belong to the wider enterprise the sources call nourishing life, which also covers diet, breathing, gymnastic regimens, drugs and sleep, and which treats the body as something to be managed over a lifetime rather than repaired when it fails.
That placement explains the vocabulary. The texts discuss the handling of qi and of jing, the generative essence, and treat conduct in the bedchamber as one of the ways either can be conserved or squandered. Their concern is duration and vitality. Moral judgement about sexual conduct, which is present in Chinese writing in quantity, is largely absent from this literature, because the literature is not asking that question.
Imperial bibliographies list bedchamber works as a recognised category alongside the other medical divisions, which is how it is known that a substantial body of such writing once existed. Most of it did not survive in China. The Encyclopedia of Taoism and the Daoism Handbook, both edited surveys of the field, set out what the category contained and how it was understood, and the atlas follows them in describing the tradition rather than reproducing any regimen it prescribes.