The three together on a single object constitute saṃyama.

Traya means three. Ekatra means “in one,” on a single point. The three are dhāraṇā, dhyāna, and samādhi.

Saṃyama is the technical term Patañjali will use repeatedly in this Pāda. It is the combined application of concentration, meditation, and absorption on any object.

While the first five limbs (yama, niyama, āsana, prāṇāyāma, pratyāhāra) prepare the ground, these three constitute the direct tool of transformation.

They are called antaraṅga, the inner limbs, in contrast with the bahiraṅga or outer ones.

From here on, Patañjali will describe the extraordinary results that arise from applying saṃyama to different objects: knowledge of past and future, understanding of other minds, invisibility, and other siddhis.

Saṃyama is the master key. The object determines which door it opens.