What is the difference between mt199 and mt999?

MT199 and MT999 are both message types used in the SWIFT network for financial messaging. The MT199 is a free-format message used for general inquiries or communications between financial institutions, while the MT999 is specifically a free-format message that does not have any predefined fields or structure and can be used for various purposes not covered by other message types. Essentially, MT199 is more focused on inquiries, while MT999 serves as a catch-all for miscellaneous communications.