OPOS or OLE for Retail POS consists of an architecture for Win32-based POS device access. OPOS is currently deployed on Microsoft Windows 95, Windows 98, Windows ME, Windows NT, Windows 2000, Windows XP, Windows Vista, and Windows CE. It also consists of a set of POS device interfaces sufficient to support a wide range of POS solutions. It provides a consistent interface to POS peripherals for use by application creators.
OPOS was the first widely-adopted POS device standard. It was initiated by Microsoft, NCR, Epson, and Fujitsu-ICL to help integrate POS hardware into applications for the Windows family of operating systems. OPOS uses COM technology, and is therefore language independent.
The first OPOS technical meeting was convened in January, 1995. The first production release, 1.01, was made in March, 1996. Its seventh release, 1.6, was in July, 2001. Beginning with release 1.7, the OPOS committee no longer releases an implementation-specific document. The UnifiedPOS document has added implementation information into an appendix.
The core membership was established with a minimal number of major players in the Retail industry, so that initial work could proceed quickly. The core committee consists of Microsoft Corporation, NCR Corporation, Seiko Epson Corporation, and Fujitsu/ICL. Following the initial release in December 1995, one representative each from Europe and Japan was added to the core group, bringing its membership to the current six. The core committee is tasked with general oversight of the initiative, while all interested parties are welcomed to attend general sessions and provide input.
OLE for Retail POS Controls adhere to the ActiveX Control specifications. They expose properties, methods, and events to a containing Application. The controls are invisible at run time, and rely exclusively upon the containing application for requests through methods and sometimes properties. Responses are given to the application through method return values and parameters, properties, and events.