The Pipeline and Hazardous Materials Safety Administration, Office of the Chief Counsel, also provides informal and formal written interpretations of the Hazardous Materials Regulations (HMR; 49 CFR Parts 100-185).  Formal interpretations are in the form of Federal Register publications and are listed below.  Informal interpretations, also listed below, are included in the Hazardous Materials Interpretations searchable database and can be identified by "CHI" in the PHMSA ID field.  Examples of the application of the HMR can also be found in Appeal Decisions.