AS3 is an implementation, not a standard. Large parts of AS3's feature set actually were considered for standardization, back in the days of the "ECMAScript 4"

AS3 is an implementation, not a standard. Large parts of AS3's feature set actually were considered for standardization, back in the days of the "ECMAScript 4" standard (in quotes because it was never released). That standard was abandoned, due to differences some dismiss as politics and others claim were due to implementation and complexity issues.