SWIFT FIN messages transmit financial information from one financial institution to another. These messages are classified into different message categories. There are 10 categories of FIN messages (Category 0 through Category 9), and each category relates to a particular topic. For example, Category 5 contains messages related to Securities.

Each SWIFT message is represented by a three-digit number (for example, MT 541). The MT represents SWIFT's “Message Type.” The first number (5) identifies the category to which the message belongs; the second and third numbers (41) identify the message type.

SWIFT updates the MT specifications every year. SWIFT Module maintains these specification changes in the swiftMT and dfdMT XML files. Based on the specified version, SWIFT Module uses the corresponding swiftMT or dfdMT files to define the IS document that is created.

For details about SWIFT specifications, see [http://www.swift.com](http://www.swift.com/). For details about the SWIFT specification versions that SWIFT Module supports, see webMethods eStandards Modules System Requirements.

The FIN format -- or MT format -- refers to how a SWIFT message should be constructed. A message format depends on the FIN category and type. The MT standard defines the following 10 standard message categories:

1. Category 1: Customer Payments and Cheques.

    Payment-related messages in which at least one party is not a financial institution.

2. Category 2: Financial Institution Transfers.

   Payment-related messages in which all parties are financial institutions.

3. Category 3: Foreign Exchange, Money Markets and Derivatives.

   Messages related to foreign exchange contracts, foreign currency option contracts, money placement or interest rate derivatives.

4. Category 4: Collections and Cash Letters.

    Messages exchanged between banks when handling documentary and [clean collections](https://www.globalnegotiator.com/international-trade/dictionary/clean-collection/).

5. Category 5: Securities Markets.

    Messages exchanged between financial institutions when carrying out [securities](https://www.techtarget.com/whatis/definition/security-finance)

6. Category 6: Commodities and Reference Data.

    Messages exchanged between financial institutions when carrying out commodity-based transactions.

7. Category 7: Documentary Credits and Guarantees/Standby Letters of Credit.

   Messages exchanged between banks that participate in the documentary credit and guarantee business.

8. Category 8: Travellers Cheques.

   Messages exchanged between issuers and agents when handling travellers cheques.

9. Category 9: Cash Management and Customer Status.

    Messages exchanged by financial institutions to report balances, interest rate changes, netting, status or bilateral key exchange.

10. Category n: Common Group messages.

     Message types that can be used in each of the other message categories.

The MT messaging model also includes a Category 0 for system messages that are used to exchange operational information between SWIFT and FIN interface operators.

Each category supports multiple message types. As noted above, the message type is indicated by a three-digit numerical identifier, which is always preceded by the letters MT. The first number represents the category, and the last two numbers indicate the specific message type within that category. For example, a message with the identifier MT 502 indicates that it is a Category 5 message with a 02 message type, which is used to request the sale or purchase of a particular financial instrument.

The message types are clearly defined in the SWIFT documentation. Each type has its own format specifications along with a description of the available message [fields](https://www.techtarget.com/searchoracle/definition/field) and whether they're required or optional. The documentation also provides information such as usage rules, size limitations, [network validated](https://www.techtarget.com/searchnetworking/tip/Network-validation-a-first-step-to-intent-based-architecture) rules, [authentication](https://www.techtarget.com/searchsecurity/definition/authentication) requirements and other guidelines.