瑜伽論記 7.27

7.27

下明念入息短時，緣此中間入息，出息亦爾等者，初從臍出乃至口鼻，或出鼻外是長出息，出息已滅入息未生，從臍至鼻中間暫時，有出息相似風。

Below, where it clarifies 'when mindful of a short in-breath, one takes this intermediate in-breath as cognitive object, and the out-breath is likewise', etc.: initially emerging from the navel up to the mouth and nose, or exiting outside the nose, this is a long out-breath; when the out-breath has ceased and the in-breath has not yet arisen, in the interim from the navel to the nose there is momentarily a wind resembling the out-breath.