Introduction

In the opening chapter of this book the concept of metadata was introduced in terms of its etymology (‘data about data’) and Bagley's first definition (‘a second data element which represents data “about” [a] first data element’). Both point out that at its centre is the idea of a conjunction between two elements: metadata always refers to something else, the data which is its referent. The nature of this relationship in many ways determines the form that the metadata will take and the relationship itself is dictated by the purpose for which it is compiled.

This immediately brings us to an important but sometimes forgotten feature of metadata: that it is constructed for a purpose; it is an artificial creation, not something that is found in the world itself. The purpose for which any metadata is compiled inevitably dictates everything about it, from the terms that it employs to describe its referent data to the way in which it is organised. The most significant impact that the purpose behind metadata can have is in determining what it encompasses and what it chooses to omit; it is inherently selective in its remit and can never claim to be universal.

Metadata should also never be seen as inherently objective: it is making a statement about the world, and this statement is a subjective one. This may seem obvious in the case of something as clearly human-created as a classification scheme; but it is also true of automatically compiled metadata such as logs of user access to web pages, where the choice of what to record is selective and so, to some extent at least, subjective.

All of the standards that will be covered in this book (and what exactly constitutes a metadata standard will be discussed shortly) have been constructed for a given purpose and with a circumscribed remit; they therefore inevitably exhibit these features of selectivity and constraint. This does allow them to be focused and so able to perform the functions for which they have been devised, but it does mean that no single one can encompass all of the metadata requirements for a digital library.