This document describes extensions to the ECMAScript language implemented in Microsoft web browsers. The extensions are in these rendering modes: IE9 Mode, IE10 Mode, IE11 Mode, and EdgeHTML Mode. IE9 Mode is based on ECMAScript Language Specification 5th Edition [ECMA-262/5]; the other modes are based on ECMAScript Language Specification 5.1 Edition [ECMA-262/51].
Section 2 of this specification is normative. All other sections and examples in this specification are informative.