OPOS, full name OLE for Retail POS, a platform specific implementation of UnifiedPOS, is a point of sale device standard for Microsoft Windows operating systems that was initiated by Microsoft, NCR, Epson, and Fujitsu-ICL and is managed by the Association for Retail Technology Standards. The OPOS API was first published in January 1996. The standard uses component object model and, because of that, all languages that support COM controls (i.e. Visual C++, Visual Basic, and C#) can be used to write applications.