This report presents the findings of two studies related to the design of symbology for electronic displays of navigation information. Experiment 1 addressed whether symbols have key features that are necessary for recognition, i.e., symbol stereotypes. Experiment 2 tested symbol-feature rules, which define a consistent way to design symbols, to determine if pilots could learn and apply them. The resulting guidelines were provided to the Federal Aviation Administration, industry, and the International Civil Aviation Organization and are documented in this report. Suggestions for evaluating symbology are also provided.