What is the meditation position in which Ananda thero became an arahant? We all know that Ananda Thero was Buddha's personal attendant -- Wikipedia says,


  In the long list of the disciples given in the Anguttara Nikaya (i. xiv.), where each of them is declared to be Prime in some quality, Ānanda is mentioned five times (more often than any other). He was named Prime in conduct, in service to others, and in power of memory. The Buddha sometimes asked Ānanda to substitute for him as teacher and then later stated that he himself would not have presented the teachings in any other way.


So my question is: after Buddha's Nirvana, Ananda Thero became arahant before the The First Council; so what is the position of meditation that Ananda Thero became arahant?
Ven. Ananda’s realization of emancipation happened when he was neither walking, standing, sitting or lying down.  Ven. Ananda was doing the walking meditation at that time.  It is interesting to note that meditation could be practiced employing any of the four bodily postures, and he never got out of his 'walking meditation..  For emancipation one has to eradicate influxes (asava) and this is how Ven. Ananda got emancipated. At that very moment when he was about to lie down, when he was between standing and lying down to sleep, just before his head hit the pillow, he became an arahant.
Nyanaponika Thera discribed it thus, in his book &quot;Great Disciples of the Buddha - Their Lives, Their Works, Their Legacy&quot;:

“He practised the four foundations of mindfulness throughout the night - sitting and walking, sitting and walking, sitting and walking. In the early hours of the morning, as he was preparing to lie down after a full night of striving, just when he has raised his legs off the ground but had not yet laid his head on the pillow, his mind was released from all cankers....”
&quot;...When Ananda was 120 years old......Ananda chose a way to die in keeping with his gentle nature: he raised himself into the air through his supernormal powers and let his body be consumed by the fire element. The relics were devided and stupas erected.&quot;