fill-in area

The area where the coverage contour of an FM translator or booster station is within the protected contour of the associated primary station (i.e., predicted 0.5 mV/m contour for commercial Class B stations, predicted 0.7 mV/m contour for commercial Class B1 stations, and predicted 1 mV/m contour for all other classes of stations). [47 CFR 74.1201]