The diamond is broken into four sections. Numbers in the three colored sections range from 0 (least severe hazard) to 4 (most severe hazard). The fourth (white) section is left blank and is used only to denote special fire fighting measures/hazards. At first glance, the Hazardous Materials Identification System HMIS (was developed by the NPCA) and NFPA labeling systems appear quite similar. Both have four sections colored blue, red, yellow and white. HMIS uses colored bars, while NFPA uses colored diamonds. HMIS attempts to convey full health warning information to all employees while NFPA is meant primarily for fire fighters and other emergency responders. Some employers use hybrids of the two systems. For example, they will use an NFPA hazard diamond, but the white section is used to denote both Personal Protective Equipment PPE and/or special hazards. Both the NFPA and NPCA (National Paint & Coatings Association, now known as the American Coatings Association), discourage mixing of the two systems in this manner. OSHA permits one to use any labeling system as long as it meets their labeling performance requirements. Thus, if you use a hybrid system at your location, your employees must be properly trained in using it and be made aware of these potential conflicts