A t is recognized as a t because it differs from other letters and because it has a number of characteristic features that correspond with the features of the other specimens of a t in the database (to which this new specimen may be added). Similarly, a text or manifestation of a version of a work may differ from that of another version, but in spite of their differences, there are also correspondences that suggest they may be subsumed under the same title. Whether or not the work this title refers to is the sum of all its variants is a matter of interpretation.