> So, essentially, JavaScript, JScript, and ECMAScript are three names for the same language.
This is a little wrong/misleading.
ECMAScript is the specification; JavaScript, JScript, and ActionScript, are various implementations of the specification. Each implementation provides additional features not described in ECMA specs, such as access to ActiveX and the local computer in JScript.
Mozilla's view is that JavaScript is a language, of which they provide two implementations: SpiderMonkey and Rhino.[1]
As far as I'm aware, MS has used JScript to use to both their original implementation and the language it implements, as well as JScript.Net being both the implementation and the language it implements. I can't find any citation for this, however.
Adobe considers ActionScript a language, with implementations including AVM.[2]
[Edit:] I just realised you could also potentially mean "implementation" insofar as they define a host environment for ECMAScript, except JavaScript especially does not: just look at the difference between SpiderMonkey-in-a-browser and SpiderMonkey-on-the-CLI.
This is a little wrong/misleading.
ECMAScript is the specification; JavaScript, JScript, and ActionScript, are various implementations of the specification. Each implementation provides additional features not described in ECMA specs, such as access to ActiveX and the local computer in JScript.