My first job out of university was working for a debt collection firm that made its own ACH engine in Perl. I remember all the 99999s and headers and stuff. I didn't work very much on the engine though (thankfully).
I was pretty shocked at just how far behind the American banking system was when I lived overseas for a bit. I wrote about it here:
I was pretty shocked at just how far behind the American banking system was when I lived overseas for a bit. I wrote about it here:
https://battlepenguin.com/tech/the-american-banking-system-i...