瑜伽論記 7.26

7.26

入息等者，景師解云：入息入時遍內身乃至臍處也。中間入息者，入息滅已出息未生，中間暫時有息相似細風。

Regarding 'the in-breath', Master Jing explains: When the in-breath enters, it pervades the internal body down to the navel. The 'intermediate in-breath' means that after the in-breath has ceased and before the out-breath has arisen, in the interim there is momentarily a subtle wind resembling breath.