The Stages of Vipassana - 12th stage of vipassana nana

The twelfth stage of vipassana nana is Adaption knowledge  (anuloma

nana).

Adaptation knowledge, or conformity knowledge, is the vipassana nana that

arises in the process during which enlightenment is attained, that is,  the

magga-víthi. This kind of knowledge conforms to the clear understanding of

the Noble Truths. Adaption knowledge is the three moments of maha-kusala

citta accompanied by panna arising in the magga-víthi. They are: parikamma

or preparatory consciousness, upacara or access and anuloma or 

adaptation. These three cittas have as their object one of the three

general characteristics. They realise the conditioned dhamma appearing at

that moment either as impermanent, or as dukkha or as anatta. Adaptation

knowledge adapts or conforms to detachment from the objects that are

conditioned dhammas.

For the person who is keen (tikkha puggala), that is, who has keen panna

and can realise the Noble Truths rapidly, there are two moments of 

adaptation knowledge, because he does not need preparatory 

consciousness (parikamma).