Office Genuine Advantage (OGA) was a program by Microsoft, similar to Windows Genuine Advantage (WGA), which required users of the Microsoft Office software to validate their copy of Microsoft Office to download non-critical updates and other downloads such as addons and samples. Starting October 27, 2006, users of Office Update were required to validate the legitimacy of their Office software in order to download files and updates. On April 15, 2008, Microsoft released Office Genuine Advantage Notifications to Windows Server Update Services as KB949810.