technique whereby a set of characteristics of a particular class of person is inferred from past experience, and data-holdings are then searched for individuals with a close fit to that set of characteristics. Dataveillance depends on the availability of data. Whereas the term 'personal data system' reflects the interests of a data collector, a term is needed that relates to the interests of individuals: Data Trail This is a succession of identified transactions, which reflect real-world events in which a person has participated. Human Identification Identification is a process whereby a real-world entity is recognised, and its 'identity' established. Identity is operationalised in the abstract world of information systems as a set of information about an entity that differentiates it from other, similar entities. The set of information may be as small as a single code, specifically designed as an identifier , or may be a compound of such data as given and family name, date-of-birth and postcode of residence. An organisation's identification process comprises the acquisition of the relevant identifying information. Contrary to the presumptions made in many information systems, an entity does not necessarily have a single identity, but may have multiple identities . For example, a company may have many business units, divisions, branches, trading-names, trademarks and brandnames. And many people are known by different names in different contexts. A variety of person-identification techniques are available, which can assist in associating data with them. Important examples of these techniques are: names - or what the person is