The corps de face is the most common position in life; it is equally used in dance.
L'epaule, the second position of the body, produced by the rotation of the torso on the hips, its direction, in principle is at an angle of 90 with the legs. There are intermediaries between 0 and 90.
In pure classical dance, we epaule always towards the back leg. But the character dances and vocabulary modern also use the shoulder to the front leg.
Le corps penche de cote. The body leaning sideways is rarer. It is quite tricky to execute. We execute relatively little on stage, and it is only used for the end of pirouettes with a partner when the male stops the female dancer by holding her at the waist.
The side leaning can accompany l'epaule in individual dances of character.
The body leaning forward is widely used. We use it in reverences and with other steps.
Note that there are two types of leaning forward. The first, which is never very pronounced, is due to the curvature of the spine above the pelvis, which Remains vertical only the ribcage reclines. It is colloquially known as the "round back." (dos rond).
The second leaning forward, can go so far as to bring the torso along the legs, upside down, is due to the rotation of the pelvis on the heads of the femurs. Only the legs remain vertical; the torso rotates from a block. In general, these two ways of bending together are combined.
Le corps penche en arriere ou cambre. The body leaning back or arched has become a movement of grace and difficulty. It is more frequent than we would think. We find it at the end of specific pirouettes in classical ballet such as Swan Lake (choreography of M. Petipa), in Character variations, Petrouchka (choreography of Fokine)
We will add to the body position, l'enselle. It is produced when we curve the lower back sticking the rear end back. Mostly in Africa, the Comic character of antique Greece, etc. This position is strictly prohibited in Classical dance
Source : Grammaire de la danse classique Germaine Prudhommeau Genevieve Guillot