Oof.
User s9w appears to be German. ACH is a USA construct. The closest analog would be PE-ACHes for SEPA, of which OP might be familiar. Without context and operating from a localized search zone, googling ACH may render results irrelevant to the topic at hand, requiring marginally more google-fu than might otherwise make sense just to embrace a hackernews thread.
Hackernews in general is pretty US-centric in terms of assumptions, and this comment is emblematic of this defect.
In the future, you could just answer the question, or you could opt out of replying entirely. You never know what constraints a person has encountered when trying to answer it on their own. For all you know, the user asking must work with an impairment or disability rendering simple web queries as taxing or arduous.
