俱舍論記 22.191

22.191

「是等流性至無如是故」者，釋頌等流，即是第五等流門。同類因生，故是等流性。非所長養，身肥大時息損減故，身瘦少時息增長故。非異熟生，斷已後時更相續故，餘異熟色無有斷已更相續故。故《正理》云「身中雖有長養、異熟風，而此息風唯是等流性。」

Regarding "It is of the nature of flowing outflow (niṣyanda) ... because there is no such phenomenon": this explains the verse's term "flowing outflow" (niṣyanda), which is the fifth topic: flowing outflow. Because it is produced from causes of similar kind (sabhāga-hetu), it is of the nature of flowing outflow. It is not nutriment-grown (aupacayika), because when the body is fat and large, the breath is diminished, and when the body is thin and small, the breath is increased. It is not fruition-born (vipākaja), because after it is interrupted, it continues again at a later time, whereas other fruition-born form does not continue again once interrupted. Thus the Nyāyānusāra states: "Although there are nutriment-grown and fruition-born winds within the body, this wind of breath is exclusively of the nature of flowing outflow."