Anupassanā: Contemplation, deep reflection, profound consideration:
The 4 fold: see: satipatthāna.
The 18 fold: see: vipassanā.
The 7 fold: The seven contemplations:
1: Contemplating constructions as impermanent, one leaves behind the perception of permanence.
2: Contemplating them as painful, one leaves behind the perception of happiness.
3: Contemplating them as not self, one leaves behind the perception of ownership.
4: Becoming disillusioned, one leaves behind delighting.
5: Causing fading away of lust, one leaves behind greed.
6: Causing ceasing, one leaves behind creating.
7: Relinquishing, one leaves behind clinging.
Pts.M. I, p. 58. - See also Vis.M XXI, 43; XXII, 114.