Its not just mainline, also on Express flights without E+. ER4s have the seatmap. Only elites can book these seats, IME - they won't sell these to non-elite's like they would E+.

On the ERJs, these elite rows are less then they were before the merger - IIRC, up to row 9 were reserved for elites at the old CO and now, I think there are only about 4, maybe 5 rows like this.