What does it indicate if an "X" or an "RQ" appears in the HM column of a shipping paper entry?

The "X" or "RQ" appearing in the HM column of a shipping paper entry signifies that the shipment is regulated by hazardous materials regulations. In this context, the "X" indicates that the shipment contains hazardous materials, while "RQ" stands for "Reportable Quantity," which denotes that the quantity of the hazardous substance meets or exceeds the established reportable thresholds. Therefore, when either of these markings is present, it alerts all parties involved in the transportation process that the shipment must be handled in accordance with specific regulatory requirements to ensure safety and compliance with environmental laws. This includes proper labeling, documentation, and emergency response planning for hazardous materials, highlighting the critical nature of adhering to regulations associated with the safe transport of hazardous substances.