A watermarking system includes an encoding data processor operable to generate at least one marked version of an original item of material by introducing one of a predetermined set of code words into a copy of the original material item. The apparatus has a code word generator operable to provide the code word having a plurality of code word coefficients, and an encoding processor operable to combine the code word coefficients with the material. Each of the plurality of code words of the set is uniquely associated with a data word having first and second fields. Each of a set of values of the first field is represented as a first part of the code word having a first plurality of coefficients, and the second field is represented as a second part of the code word having a second plurality of coefficients.