What is indicated by red and white lines designating an envelope?

The designation of red and white lines forming an envelope typically indicates that the area will be occupied by parked aircraft. This visual cue is vital for maintaining safety and order in the airport environment, especially to guide fire fighters, aircraft operators, and other personnel in understanding which zones are designated for parking. Clear identification of these areas helps prevent accidents by ensuring that everyone knows where vehicles can move and where they cannot.

In contrast, other choices represent different designations and uses of space on the airfield, which do not pertain specifically to the function of parked aircraft. Understanding these markings is crucial for operational efficiency and safety in an airport setting.