Iyengar: Moral injunctions, fixed observances, posture, regulation of breath, internalization of the senses toward their source, concentration, meditation, and absorption of the consciousness in the self, are the eight constituents of yoga.
This sutra lays out the eight fold path of yoga and the rest of the sutras in this pada work with this eight fold path (up to patryahara).
Bryant: The eight limbs are abstentions, observances, posture, breath control, disengagement of the senses, concentration, meditation, and absorption.
Here is another prescription to attain Samadhi. Sutra 1.12 presented one way, sutra 2.1 presented another way (kriya yoga) and both sets of injunctions can be found within the first two limbs.
Taimni: Self restraints, fixed observances, posture, regulation of breath, abstraction, concentration, contemplation, trance are the eight parts (of the self discipline of Yoga).
Taimni discusses the order of this path and that Pantanjali most likely wanted the sadahaka to practice this path in order. However, each limb can be practiced on its own.
Carrera: The eight limbs of Yoga are abstinences, observance, posture, breath control, sense withdrawal, concentration, meditation, and contemplation, absorption or superconscious state.
Carrera points out that these eight limbs “seamlessly integrate selfless, active participation in life with introspection and contemplation…to encourage self knowledge, expand and transform consciousness..”
He has an interesting comparison to Buddhist teachings on suffering.