俱舍論記 24.23

24.23

「論曰至名為上流」者，此不還者通約三界總說有七，今且就行色界差別有其五種。列名可知。五中前四，唯於此身定般涅槃故，所以偏與般涅槃名。上流容有受多生者方般涅槃，非諸上流皆定涅槃，以不定故所以不言般涅槃也。言釋名者，此於二趣中間般涅槃故，名中般涅槃。如是應知，此於初生已、此由有行道、此由無行道般涅槃故，名生般等三人。此二生已上向上流故，名為上流。

Regarding 'The treatise says... is named upper stream (ūrdhvasrotas)': these non-returners, generally speaking across the three realms, are of seven kinds in total; now, taking their distinctions in the form realm, there are five kinds. Their names are listed and can be known. Among these five, the first four definitely enter parinirvāṇa in that very body alone; therefore, they are specifically given the designation of 'entering parinirvāṇa' (parinirvāyin). The upper-stream type allows for those who experience multiple rebirths before entering parinirvāṇa; it is not the case that all upper-stream types are determined to enter nirvāṇa [there], and because it is undetermined, 'entering parinirvāṇa' is not mentioned. As for explaining the names: because this one enters parinirvāṇa midway between two destinies, it is called 'one who enters parinirvāṇa in the intermediate state' (antarā-parinirvāyin). In this way it should be understood: because this one enters parinirvāṇa right after being born, because this one enters parinirvāṇa by means of an active path (sābhisaṃskāra-mārga), and because this one enters parinirvāṇa by means of an effortless path (anabhisaṃskāra-mārga), they are called the three persons: 'one who enters parinirvāṇa upon birth' (upapadya-parinirvāyin), etc. Because this one, after taking rebirth twice or more, streams upward toward higher states, it is called 'upper stream' (ūrdhvasrotas).