(Yesterday, 5:59 pm)Storx wrote Aye no arguments about South Hylton.
But I personally read it as
3TPH | Airport - Sunderland - Heworth (Terminate)
3TPH | Airport - Sunderland - Heworth - Monkseaton
Why it's like that I don't know but the line from Monkseaton to Heworth on the red line is definitely only 3 TPH (narrow line), well and is says it on the side.
Peaks maybe? That doc will have been written before they temporarily removed them from the timetable, but the ambition is still to bring them back. It needs them, especially on a morning.