The border has higher priority than pixels but lower priority than the black colour output when HSYNC/VSYNC are active.
The DISPTMG signal is composited from its 3 internal subcomponents: HBORDER (Horizontal), VBORDER (Vertical), IBORDER (Immediate) by using the NOR function. DISPTMG is "0" if at least one of its subcomponents is "0".
=== Immediate border ===