BAI2
The American file format for bank statements and balance reports, playing the role in the US that MT940 plays almost everywhere else.
It comes from the Bank Administration Institute, with a spec dating from the late 1980s. A file is comma-separated text built from numbered record types: 01 for the file header, 02 for the group, 03 for each account and its balances, 16 for every transaction and 88 for continuation lines. Everything is tagged with three-digit type codes, so 010 is the opening ledger balance and 015 the closing one. Each level ends in a trailer that counts records and totals amounts.
The spec left a lot open, and banks filled the gaps differently. Anyone integrating with several US banks ends up writing one parser per bank in all but name. Stewardship later passed to the standards body X9, but pressure to move to camt.053 grows as the rest of the payment chain starts speaking ISO 20022.