Well, decide which ever is the canonical reference and stick all the version in that one, than just alias the exiting ones to specific versions of it.

You can totally alias "ECMA-262-51" to "ECMASCRIPT-51" if ECMASCRIPT.versions["51"] exists.

Not sure whether or not we want to include dots in version numbers and/or use "ECMASCRIPT" or "ECMAScript" or have both.