Abstract: A semiconductor wafer (50) is inscribed by a laser scribe system with a numeric wafer identifying number in binary dot-array encoded form to facilitate machine readability. A matrix (20) of predetermined dot locations on the wafer defines a series of parallel columns (e.g. 28) of dot locations, each column corresponding to a respective digit of the ID number. In each column, a number of dots equal to the numeric value of the corresponding digit plus one (N+1) is marked in a contiguous series starting from a baseline row (27,39) of the matrix. A pair of dot arrays (20,30) thus formed are aligned for convenient validity checking. The wafer area required for a dot-array encoded ID number is less than the area required to write a single digit of the ID number in alphanumeric form (14).