NOM, or Norma Oficial Mexicana, is a set of official, compulsory standards and regulations that apply to businesses operating in Mexico. They are prepared by the General Directorate of Standards, which is the group that represents Mexico in the International Organization for Standardization (ISO). NOM-18 is from the Ministry of Labor and Social Security and was first put into force in the year 2000. This set of standards describes the system used for identification and communication of risks and hazards associated with dangerous chemical substances in the workplace.
NOM-18 is their version of the Globally Harmonized System (GHS) which is used throughout the globe and is apart of the United States' official HazCom regulations. Companies that create, use, store, or transport any type of hazardous chemical need to be familiar with what NOM-18 is, and its meanings, if they are going to do any type of business in Mexico.