What does 流通 mean as a metaphor for Nirvāṇa?

Question

In the 890th sūtra of the Saṃyuktāgama, at the end of the sūtra, the text transmits a number of metaphors, such as "the deathless" (不死) and "the island" (洲渚). One of these terms is "流通" which appears to mean "to circulate, to propagate, to distribute, to pass down," but seems to be being used as a noun. What does it mean in this context?

Full text of section:

如無為，如是難見、不動、不屈、不死、無漏、覆 蔭、洲渚、濟渡、依止、擁護、不流轉、離熾焰、離 燒然、流通、清涼、微妙、安隱、無病、無所有、 涅槃，亦如是說。

As a further question, what is the fine difference between introducing the first element of the list with just "如" and the second element with "如是?"

Thank you for your time, all.

Answer 1

如無為・如是難見・不動・不屈・不死・無漏・覆蔭・洲渚・濟渡・依止・擁護・不流轉・離熾焰・離燒然・流通・清涼・微妙・安隱・無病・無所有・涅槃・亦如是說

the text quoted from 雜阿含經 31 卷, 890th [0224b07]

“洲渚” is islands, islets in a river, used as a metaphor for “asylum”

considering a river, there’s this bank (此岸) where on is, and the other bank (彼岸) where one want to go. so, to swim across the river, one might be tired, then, an island / islet in midway gives a chance for the swimmer to repose.

不流轉・離熾焰・離燒然・流通・清涼

“流通” is related to “不流轉”, as “清涼” is related to “離熾焰・離燒然”; describing a notion in positive terms, then in negative terms.

my best guess is, “不流轉” is derived from “not in the cycle of death and rebirth“ (不生死流轉), that “流通” means the transcendent state, that “free from the such cycle”, aka nirvana.

如無為，如是

about the “如”, depends on the writing style in english, one might interpreted it as “if” & “it should be”; or “such” & “such would be”.