An apparatus and method for machine-updating of prototypes—for example, during design of digital objects, or content-management—has input means (15) for inputting descriptive classifiers (tags) that a user assigns to prototypes and a tag model generator (20) that uses machine learning techniques to produce a model of the association between the assigned tags and the values of quantifiable, non-subjective attributes of the tagged prototypes. In order to obtain a desired updating of a current prototype, the user issues a command which defines the desired variation of the current prototype by referring to one or more conditions that should be met by specified tags of the updated prototype. The prototype-updating apparatus/method has a prototype updater (30) that identifies a suitable updated prototype whose tags meet the condition(s) specified in the user's command and which, globally, is fairly similar to the pre-update prototype. The user can, thus, express instructions for prototype-updating using his own terminology.