What type of cylinder markings are required for EANx cylinders?

The correct response highlights that EANx (Enriched Air Nitrox) cylinders must be marked with both the percentage of oxygen and the maximum operating depth. This information is crucial for divers to safely plan their dives. The percentage of oxygen indicates how enriched the gas is compared to air, which directly affects the diver's no-decompression limits and potential for oxygen toxicity. Knowing the maximum operating depth helps divers avoid dangerous exposure to higher pressures that could exceed safe limits for oxygen.

The other types of markings, such as the manufacturer's name, cylinder volume, or weight, do not provide the critical information needed for safe use of the EANx cylinder in a diving context. The key focus when using enriched air is to understand its composition and how it influences dive planning and safety, making the markings of oxygen percentage and depth limitations essential for safe diving practices.