After Flash 5 introduced ActionScript in 2000, developers combined the visual and programming capabilities of Flash to produce interactive experiences and applications for the Web. Such Web-based applications eventually came to be known as "Rich Internet Applications" . In 2004, Macromedia Flex was released, and specifically targeted the application development market. Flex introduced new user interface components, advanced data visualization components, data remoting, and a modern IDE . Flex competed with Asynchronous JavaScript and XML  and Microsoft Silverlight during its tenure. Flex was upgraded to support integration with remote data sources, using AMF, BlazeDS, Adobe LiveCycle, Amazon Elastic Compute Cloud, and others. As of 2015, Flex applications can be published for desktop platforms using Adobe AIR. Between 2006 and 2016, the Speedtest.net web service conducted over 9.0 billion speed tests using an RIA built with Adobe Flash. In 2016, the service shifted to HTML5 due to the decreasing availability of Adobe Flash Player on PCs. As of 2016, Web applications and RIAs can be developed with Flash using the ActionScript 3.0 programming language and related tools such as Adobe Flash Builder. Third-party IDEs such as FlashDevelop and Powerflasher FDT also enable developers to create Flash games and applications, and are generally similar to Microsoft Visual Studio. Flex applications are typically built using Flex frameworks such as PureMVC.

Based on the above article, answer a question. What version of ActionScript is used for RIAs?
ActionScript 3.0