http://www.globalsecurity.org/military/library/policy/army/fm/101-5-1/f545-aca.htm Gumball Chart
The gumball chart provides a clear picture of the status of designated elements using a color code established in the unit standing operating procedures. The chart assists the commander to quickly assess the status of critical elements and assists the staff to focus on problem areas. The color code chosen should be consistent throughout all echelons of the command. The following is a commonly used color code: GREEN indicates that the unit is at 85 percent or greater strength (combat capable); AMBER indicates that the unit is at 70 to 84 percent strength (combat capable with minor deficiencies); RED indicates that the unit is at 50 to 69 percent strength (combat ineffective, unit has major losses or deficiencies); and BLACK indicates that the unit is at less than 50 percent strength (requires reconstitution before next mission). See the example in Figure C-2.
Figure C-2. Example of Gumball Charts Note:The circles (gumballs) would be filled in with the appropriate colors (GREEN/AMBER/RED/BLACK)