What is SpreadElement in ECMAScript documentation? Is it the same as Spread syntax at MDN?

Question

At ECMAScript specification the SpreadElement is described

SpreadElement[Yield]:
...AssignmentExpression[In, ?Yield]

Is this the same as th

Answer 1

SpreadElement is just a name in the ES6 grammar for spread "operator" together with its argument when in an Array literal:

SpreadElement[Yield]:
    ... AssignmentExpression[In, ?Yield]

So, SpreadElement in [a, b, ...c] is ...c; spread "operator" is .... (scare quotes because it is not a real operator in the same sense that, e.g. - is.)

The name of the grammar rule being used in function calls will be different, as it is a different grammatical context (it's just one kind of ArgumentList).