What does a square symbol indicate regarding flammable materials?

A square symbol regarding flammable materials is typically used to indicate flammable liquids. This classification is important in the context of safety and handling, as flammable liquids can pose significant risks in various environments, especially in aviation and industrial settings. The square shape serves as a recognizable and standardized warning to indicate the presence of substances that can easily ignite and cause fire hazards. Understanding this symbol helps personnel take appropriate precautions when dealing with these materials, such as ensuring proper storage, handling, and transport protocols are followed to minimize the risk of accidents.