bb is the color's blue component ... For example, bright red is specified as CXFF0000, white as CXFFFFFF, black as CX000000, and green as CX00FF00. Any combination of the color components is valid.

like a black-and-white one, a monochromatic palette (one color, different shades or tones), or a primary color palette (red, blue, and yellow). Note: Go to this CF article for a more in-depth ...