The present invention relates to a method for forming a mark reference list using a database including a register of mark-forming objects in the form of a sample array, and a mark array. According to this method, a mark is compared with each sample of the sample array, match indexes of the mark and said each sample are determined based on said comparison, and a list of high match indexes of the mark and the samples is formed. The decision that a mark should be included into the reference list is made, if the match index of a query sample and the mark is higher than the lowest index of the list of high match indexes of the mark and the samples.