The display on the left has a PPM "dot" with a VU "bar".  The color of each segment has been fixed according to its position, which does not take full advantage of the dynamic tri-color capability of the bargraph.  The bargraph can be supplied with fixed single-color LEDs in each segment, or even monocolor (all segments the same color). However, the standard bi-color (red-green) version permits the color thresholds to be changed easily via changes in the driver program, thereby avoiding the hassle of matching bargraphs having custom segment-color configurations to particular customer scale requirements.

The middle and right bargraphs simultaneously show all three level measurements by color-coding:   PPM is amber, VU is green, and Loudness is red.  These types of display take full advantage of the bi-color red-green segments.  It would also be possible to indicate additional parameters such as overrange, underrange, peak hold, etc. by blinking, flashing, or reverse-video modes.  One or more reference levels, such as a "Zero" level might also be shown by means of fixed-position segment(s).