Internet Explorer does not include any native scripting functionality. Rather, exposes an API that permits a programmer to develop a scripting environment to be plugged-in and to access the DOM tree. Internet Explorer 8 includes the bindings for the Active Scripting engine, which is a part of Microsoft Windows and allows any language implemented as an Active Scripting module to be used for client-side scripting. By default, only the JScript and VBScript modules are provided; third party implementations like ScreamingMonkey (for ECMAScript 4 support) can also be used. Microsoft also makes available the Microsoft Silverlight runtime (not supported in Windows RT) that allows CLI languages, including DLR-based dynamic languages like IronPython and IronRuby, to be used for client-side scripting.