OFX uses an AppId and AppVersion to identify the application that is communicating with the OFX server. For example, the AppId for MS Money is “Money”, and the AppVersion for Money 2007 is “1600”. The server can choose to serve or deny your OFX request based on this information. That’s why I get a letter from my bank every year telling me that they are phasing out support for x version of some piece of software.
For lists of AppId and AppVersion values for Microsoft and Intuit products, look here:
Money: http://www.microsoft.com/money/fi/supportver.msp (edited, Microsoft removed this link, see update below) (edited, Intuit removed public access to this link, see update below)