In the NFPA Diamond classification, what is indicated by a class '4' in the stability/reactivity category?

In the NFPA Diamond classification system, a class '4' in the stability/reactivity category indicates that a substance is capable of detonation under normal conditions. This classification signifies that the material poses a significant and immediate risk due to its instability and reactivity. It is crucial for laboratory safety and emergency response teams to recognize such substances, as they require stringent handling and storage protocols to mitigate the risk of unintended detonation or explosive reactions. This classification informs users that they must adhere to the highest safety standards when working with or near these highly reactive materials.