How can high-pressure cylinders containing aviation oxygen be identified?

High-pressure cylinders containing aviation oxygen are identified by their green color and the label stating 'AVIATOR'S BREATHING OXYGEN.' This designation helps differentiate aviation oxygen from other gases and ensures that personnel can recognize it quickly in various situations, especially in emergency scenarios where the correct type of oxygen needs to be accessed rapidly. The specific green color combined with the labeling standard is crucial for safety, as it denotes that the contents are intended for human consumption at high altitudes where supplemental oxygen is necessary. This standardization across the industry helps maintain consistency and avoids confusion that could arise due to the presence of other gas types and colors.