Hazmats shipped globally are given a 4-digit number preceded by which letters to identify it?

Hazardous materials that are shipped globally are assigned a four-digit identification number, which is preceded by the letters "UN." This designation is critical for ensuring safety during transportation by providing relevant information to responders and regulatory bodies about the nature of the hazardous materials being transported. The "UN" stands for the United Nations, which established this system to promote uniformity in identifying hazardous goods. It is used internationally and enhances the ability of handling and emergency personnel to respond appropriately in case of spills or accidents involving these materials.

The other options do not fulfill this specific role. "ISO" refers to the International Organization for Standardization, which establishes various international standards but is not used for identifying hazardous materials in transport. "HAZ" does not represent a recognized prefix in hazardous materials identification. "MSDS" stands for Material Safety Data Sheet, which is a document that provides safety information about a material but does not serve as an identification number for shipping the material. Therefore, the correct identification prefix for internationally shipped hazardous materials is "UN."