The aim of the paper is to discuss the distinction between characterisation (classification) and denomination (naming, identifying) in the context of information systems (IS). The paper has a special focus on the design of identifiers, i.e. terms used for identifying individual phenomenon. The reason for this is that the distinction between denomination and characterisation is especially important when designing identifiers. Identifiers e.g. article numbers, telephone numbers, e-mail addresses and personal numbers, constitute an important part of the information infrastructure of companies and society as a whole, and therefore it is crucial that these terms are well designed. The paper illustrates that who designs, assigns and withdraws electronic identifiers is a significant economic and policy issue both within companies and for society as a whole, with farther reaching consequences than often perceived at first glance