1. Directory

An electronic directory is a specialized database whose primary function is to return one or more attributes of an object, using multi-criteria search functions. Objects can be very diverse in nature. For example, a directory object may represent a person, in which case the attributes of that object would be surname, first name, telephone number, etc. Let's take another example (already mentioned above): an object might represent a printer, and the object's attributes would be the printer's various names, its network address, its geographical location, and so on.