At the time of attaining the fourth vision, the yogin reaches the Rainbow Body ('ja' lus) of which four modalities are described in the texts: 1. the Body of the Great Transfer ('pho ba chen po), 2. the Great Rainbow Body ('ja' lus chen po), 3. the Small Transfer ('pho ba chung ngu) and 4. the Small Rainbow Body ('ja' lus chung ngu).
This seems to be a translation of Dudjom Lingpa's description of the rainbow body, I skipped through most of the site because it was giving togal instruction publicly but this portion is relevant:
Those having superior faculties are liberated as a great transference embodiment, extending infinitely into the all-pervasive dharmakaya, like water merging with water, or space merging with space. Those having medium faculties attain buddhahood as a great rainbow body, like a rainbow vanishing into the sky. When the ground clear light arises, for those having inferior faculties the colors of the rainbow spread forth from the absolute nature, and their material bodies decrease in size until finally they vanish as rainbow bodies, leaving not even a trace of their aggregates behind. That is called the small rainbow body. When the ground clear light arises, the material bodies of some people decrease in size for up to seven days, then finally only the residue of their hair and nails is left behind. The dissolution of the body into minute particles is called the small transference. For those of superior faculties this dissolution of the body into minute particles may occur even during the Breakthrough.
The Small Transference (atomic body) actually is not a "rainbow body" although rainbows may manifest when it happens.
Jyoti, just curious, have you actually received transmission of togal teachings?