DS CWA 16374-61:2012 Extensions For Financial Services (Xfs) Interface Specification Release 3.20 - Part 61: Application Programming Interface (Api) Service Provider Interface (Spi) Migration From Version 3.10 (Cwa 15748) To Version 3.20 (This Cwa) Programmer's Reference Specifies the technical specifications for the CEN/ISSS eXtensions for Financial Services (referred to hereafter as ""XFS"" for brevity).