1. In a system wherein a memory stores a plurality of sets of data, each set having been derived from a handwritten template signature and which data set uniquely characterizes that signature, and a set of data derived from a handwritten specimen signature is to be compared with one or more of said template signature data sets to determine whether the specimen signature was written by one of the persons who wrote the template signatures, a method comprising: selecting some of the data from said specimen signature data set, establishing a range of acceptable values about the values of said data, deriving from said memory those template signature data sets wherein the data which corresponds to said selected data has a value which falls within said range of acceptable values, comparing each said derived template data set with said specimen signature data set for determining which template data set provides the optimum comparison result with said specimen signature data set, and indicating which of the template data sets provides said optimum comparison result.