Unlike regular LCD, the reference monitor NEC 2490WUXi has especially solid black color – it does not produce glow if you see from an angle in darkness. Letters A-TW usually attributed to this excellent performance of H-IPS. Although we have never had any official explanation from the manufacturer, it’s said that the presence of a polarizer makes black ever-black.
In the extremely worst case (diagonal view) black color on the NEC 3090 has some colored tint similar to a regular LCD panel (in the picture it’s 27” PVA):