'du shes med 'du shes med min
see also 'du shes yod min med min [RY]
1 of snyoms par 'jug pa dgu [JV]
Neither Conception nor Non-Conception. DKC
Discussion
The fourth and highest of the Four Formless realms, also called the Peak of Existence. Its name comes from the training: a being who has achieved the level of Nothingness enters the preparation for Neither Conception nor Non-Conception. This being considers course conceptions disturbing, but the state of utter non-conception to be inferior. Thus they enter a state where there is no coarse conception, but it is not non-conception because there is still subtle conception.
Although this is frequently translated as "neither perception nor non-perception," see the discussion of the word 'du shes for the reasons why it is better to say conception than perception. DKC