DS CWA 15748-61:2008 Extensions For Financial Services (Xfs) Interface Specification - Release 3.10 - Part 61: Application Programming Interface (Api) - Service Provider - Interface (Spi) - Migration From Version 3.0 (Cwa 14050) To Version 3.10 - Programmer's Reference Purposes to promote a clear and unambiguous specification defining a multi-vendor software interface to financial peripheral devices.