This document catalogs the symbols presented with the various interfaces used by Federal Aviation Administration Airway Facilities specialists. It includes a high-level overview of each system and the symbols and coding conventions used. These data were collected through analysis of software specifications, computer-based instruction manuals, and field site visits. The visits to field sites allowed verification of information from other sources and provided information about the environments that can affect the discrimination of visual symbols. Researchers used the information from the Human Factors Design Guide, International Organization for Standardization standards, and other sources to provide recommendations for visual symbols. The researchers used this information to evaluate the symbols used at Maintenance Control Centers, taking into consideration the observed environmental conditions, and provided recommendations toward a goal of symbol standardization.