| frame | [[Shri Singha]] Category of pith instructions | Pith Instructions (Tib. མན་ངག་སྡེ་, mengakdé, Wyl. man ngag sde) — one of the three classes into which Manjushrimitra divided the Dzogchen teachings. Shri Singha arranged the teachings of the Pith Instruction class into four cycles:
Khenpo Namdrol explains:
:“These four great cycles present the Trekchö teachings in a similar way, but where they differ is in the clarity, explicitness and detail of how the Tögal teachings are given.
:Shri Singha gave the outer, inner and secret cycles of the category of pith instructions to both Vimalamitra and Jñanasutra. He transmitted the innermost secret cycle to Jñanasutra, who then passed it on to Vimalamitra.”
The root tantra of the category of pith instructions is the 'Reverberation of Sound' Tantra (Tib. སྒྲ་ཐལ་འགྱུར་, dra tal gyur).