Wikipedia
UnifiedPOS or UPOS is a world wide vendor- and retailer-driven Open Standard's initiative under the National Retail Federation, Association of Retail Technology Standards (NRF-ARTS) to provide vendor-neutral software application interfaces (APIs) for numerous (as of 2011, thirty-six) point of sale (POS) peripherals (POS printer, cash drawer, magnetic stripe reader, bar code scanner, line displays, etc.).
The goal is to allow retailers freedom of choice in the selection of POS peripheral devices by the creation, utilization, and promotion of standardized connectivity. UnifiedPOS is an abstraction standard that contains appendices which provide specific platform implementation information for Microsoft OLE and .NET Windows OS and Java for other OS (Linux) environments.
Developed by a team of joint retailer and industry technical experts following published policies and procedures, UnifiedPOS provides a consistent and exact framework for programming point of sales devices that is platform-independent and vendor-neutral.
Recent efforts (2010-2011) by the UnifiedPOS committee include provisions for local and remote POS peripheral support through a supplemental Web Services for point of service (WS-POS 1.1) standard. In addition, an increasing focus on using XML language commands to control the POS devices can be seen in the XML-POS Appendix in UnifiedPOS Version 1.13 standard.