Abstract: A bar code label candidate is framed in a stream of scanner-generated data by a circuit which counts the width of each pulse and which accumulates a fixed number of pulse width values on a rolling basis to provide overlapping basic unit signals. Each basic unit signal represents a potential N-pulse character. Basic unit signals occurring at N intervals are compared in a comparator circuit to determine whether predetermined character-indicating relationships exist. Character-indicating signals are accumulated in registers. Outputs from these registers are decoded to determine whether a label candidate (appropriate type and number of apparent characters in appropriate time sequence) has been found.