What marking is required on the outer container holding compatible hazardous materials?

The requirement for marking the outer container holding compatible hazardous materials is best represented by the term "OVERPACK." This marking indicates that the container is used to consolidate smaller packages of hazardous materials for ease of handling and transportation without compromising safety. It signifies that the container holds multiple packages that are individually marked according to regulations, and it must comply with specific standards set forth by various regulatory bodies.

Using "OVERPACK" allows for correct identification of the contents while ensuring that the packages maintain their own labeling and hazard information. This marking helps transport personnel and emergency responders to understand that the container holds more than one hazardous material package, promoting safety and compliance during handling and transport.

Other options, while related to hazardous materials, do not specifically denote the status of a container that is consolidating smaller packages. For instance, "HAZMAT" is a general term for hazardous materials and does not provide specific information about the packaging situation. "DANGEROUS" lacks the specific connotation related to the consolidation of hazardous materials in overpack situations. Lastly, "CHECK BEFORE LOADING" serves as a reminder for safety checks rather than a marking requirement for identifying outer containers holding hazardous materials.