Three categories or three classes (Tib. dé sum; Wyl. sde gsum) — the three categories into which Mañjushrimitra divided the Dzogchen teachings he received from Garab Dorje:
- the outer category of mind (semdé),
- the inner category of space (longdé), and
- the category of pith instructions (mengak dé).
Oral Teachings Given to the Rigpa Sangha
- Sogyal Rinpoche, Paris, 26-27 June 1982, the 'Seven Stages of the Categories of Mind: Semdé, Longdé and Mengakdé'.
- Tulku Thondup, The Practice of Dzogchen (Ithaca: Snow Lion, 1989), Part I, 'Three Divisions of Atiyoga', pages 47-88.