Does anyone know what they indicate? I assume the exclamation mark probably means non-legal broadcast colours...is that correct? I've also seen a "P" inside a yellow triangle: what does that mean?
Hover your mouse over the triangle and it will tell you - it indicates whether the color chosen is outside of the NTSC (!) or PAL (p) gamut. If you click the patch below the triangle, it will pick the closest legal color for you...