An entry named for yoga itself, describing a seat with the breath held in it, is the clearest statement the classical corpus makes about what its posture lists were for. The postures are not the practice. They are the arrangement of a body that makes the practice possible, and the practice is what the remaining lessons of the Gheranda Samhita and the remaining chapters of the Hatha Yoga Pradipika describe: breath restraint, the inner locks, the seals, and the states the tradition says follow from them.
That ordering is visible everywhere in the texts once it is looked for. The posture chapters are short. The seats are described with great precision about where a heel goes and cursory indifference to anything that does not affect long sitting. The claims attached to individual postures are about heat, disease and the channels of the subtle body, which are the concerns of the breath chapters.
Mallinson and Singleton's Roots of Yoga sets the primary literature out in translation and shows how small a proportion of it asana occupies. Mark Singleton's Yoga Body follows the reversal, in which posture became the visible whole of the practice for most of the world during the twentieth century. Yogasana, sitting at the end of a list and named for the thing the list serves, is where the older proportion is stated in the corpus's own voice.