AssignmentExpression grammar

Maybe I have some fundamental misunderstanding but can someone explain how AssignmentExpression can produce a typical rhs (e.g. a literal value) of an assignment, such as with the grammatical construct

    var BindingIdentifier = AssignmentExpression

(i.e. var BindingIdentifier Initializer as given in section 13.3 of ecmascript)

AssignmentExpression[In, Yield]:
    ConditionalExpression[?In, ?Yield]
    [+Yield]YieldExpression[?In]
    ArrowFunction[?In, ?Yield]
    LeftHandSideExpression[?Yield] = AssignmentExpression[?In, ?Yield]
    LeftHandSideExpression[?Yield] AssignmentOperator AssignmentExpression[?In, ?Yield]

    AssignmentOperator: one of
    *= /= %= += -= <<= >>= >>>= &= ^= |= **=