ISO20022
ISO 20022 is widely used financial message standard, covering messages sent between different organizations. These messages include credit transfer and direct debits as well as payment status reports and account statements.
Characteristics of ISO 20022 are that messages are structured, well documented and linked to the business components, meaning that they can easily be linked to the back-office applications, such as ERP systems. In addition, the ability to reuse business and message components across all messages is one of ISO 20022's core advantages.
The messages are defined by ISO 20022 Universal financial industry message scheme (UNIFI) and are based on XML (Extensible Mark-up Language). Full definition of these messages from ISO 20022 web site: http://www.iso20022.org/. SEPA payment messages are a subset of certain ISO 20022 messages.
Wiki page business rules in pain.001.001.03 show an example on what types of business rules exist in one of the messages depcited by ISO 20022.
XMLdation validator is able to validate messages based on ISO 20022. Example error report can be seen here
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