What section of the Chart Supplement provides decoded meanings for airport entry items?

The section of the Chart Supplement that provides decoded meanings for airport entry items is the Legend. This part is crucial for understanding various symbols, abbreviations, and other notations that may be used throughout the Chart Supplement documents. The Legend serves as a guide to interpret the information presented, ensuring that pilots and air traffic controllers can effectively communicate and understand the specifics related to different airports.

In contrast, the Index is primarily a navigational tool that aids users in locating specific pages or sections within the Chart Supplement. The Airport Directory section contains detailed information about each airport, such as runways, communications frequencies, and services available, but it does not provide the symbolism explanations present in the Legend. Meanwhile, the Notes section is typically used for supplementary information about the charts and may include important updates or alerts, but it does not serve the function of decoding symbols or abbreviations. Thus, the Legend is the essential component for understanding airport entry item meanings.