A method and an apparatus are provided for interrogating bits of a data frame. The apparatus comprises configurable logic that can be reconfigured to enable the apparatus to vary its configuration in accordance with various criteria to make it suitable for use in different domains. The apparatus locates and selects a bit pattern from a data frame for interrogation, compares a comparison bit value to the selected bit pattern to obtain a comparison result, and determines a location to which the comparison result is to be routed. The method relates to the steps of selecting the bit pattern from the data frame, comparing the selected bit pattern to the comparison bit value to obtain the comparison result, and determining the location to which the comparison result is to be routed. The logic of the apparatus is variable to enable the bit pattern to be interrogated to be varied, to enable the comparison bit value to be varied, and to enable the location to which the comparison result is routed to be varied.