An apparatus comprising means for processing data representative of an optically readable code, means for detecting, from the data representative of the optically readable code, a symbol indicating that the code is a member of a set of codes including at least two optically readable codes, means for collecting, from the data representative of the optically readable code, one or more collection symbols, and means for assessing, on the basis of the collection symbols collected from at least two optically readable codes, if a predetermined collection criterion for finishing the collections is fulfilled.