The MicroFirst Netcue system is designed to deliver real-time on-air schedules to affiliates, and automate the process of substituting commercials sent from the head-end with local commercials. The schedule data is transmitted within the Vertical Blanking Interval (VBI) in the CBS satellite feed. The data is received by a VBI modem, and then decoded and presented to the user via MicroFirst's Netcue system.