ISO 20022
The common standard for financial messages, which has replaced the banks' fixed-width text formats with XML and rich, structured data.
First published in 2004, it is really a methodology rather than a single format. A data model of business concepts generates the concrete messages, usually as XML. These are grouped into families with four-letter prefixes, for example pain for customer payment initiation, pacs for interbank payments and camt for statements and reconciliation.
Its predecessor was Swift's MT format from the 1970s, with numbered fields and hard character limits that forced addresses like "1 HIGH ST LDN" into a free-text field. SEPA was built on ISO 20022 from the start, and Swift moved cross-border payments over during a coexistence period that ended in November 2025. The upside is data that machines can read end to end. The downside is that every bank still has its own opinion about which optional fields are mandatory.