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1. Introduction

This document offers a guide to the important standards, recommended practices and reference works in the field of the preservation and conservation of documents of all types. It does not attempt to include all the publications for a particular type of document - only the most important ones. The level of authority of the publications varies. They range from de-facto standards that are widely accepted by the practitioners in the field to formal International Standards produced by the International Standards Organisation (ISO). International co­operation in standardisation work is generally coordinated by ISO which defines itself as:

" - - a world­wide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organisations, governmental and non­governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (TEC) on all matters of electrotechnical standardisation."

A standard can be used either as a guideline or as a source of specifications. Standards by themselves, however, are only an introduction to the subject. In the use of a standard it is important that the user is familiar with the subject in question, thus being able to relate the information and the circumstances to each other. In particular, standards and other publications must not be used as the sole source of information about conservation techniques. Seek advice from experts and practitioners in the field before trying to conserve any document. Much protection can be offered by ensuring that documents are stored in appropriate containers, are not subject to fluctuations of temperature and relative humidity and are handled with care. Specialist treatment is available for all types of document, from the most ancient to the most recent, and professional advice should be sought from appropriate museums, libraries and archives before undertaking any work on them. Specific advice is also often available in the standards quoted.

Standards are very important, but unfortunately standards often become modified by users after some time which can make the standard out-dated and even impede the easy exchange of information. A good example of this are the Machine Readable Cataloguing Formats (MARC) which are all based on the ISO 2709-1981 standard. However, many countries have developed their own national version and this makes the exchange of bibliographic records more difficult. Other examples include the many Document Type Definitions (DTDs) which are based on the SGML standard.

The documents in the archives and libraries of the world are indispensable sources for many scholarly disciplines. They are also sources for more informal purposes: self-education, entertainment and general interest. No evaluation of politics, history, everyday life, music and performing arts would be possible without these documents.

Information should be available to all people as freely and as easily as possible. Preservation of that information in all formats ensures access and should be pursued actively for that reason.

The safeguarding of all these documents has until recently been primarily associated with the keeping of books and other written materials. This is partly, perhaps, because textual libraries have existed for more than 4000 years, while audio­visual archives have been in existence for only less than 100 years. The newest forms of document have been in common existence for less than a decade. There are, however, fundamental differences between the different types of documents.

Printed matter represents human thoughts by the use of a stock of symbols. A certain amount of redundancy is intrinsic in speech and writing. Letters, sometimes even words, may be omitted without any real detriment to communication. Good examples are the scripts of Semitic languages which generally do not represent all vowels which are spoken. But still, even complex texts like philosophical tracts can be communicated by these languages.

In contrast, the audiovisual document is an analogue representation of a physical status or event: every part of such a document is information. While a speck of mould in a book does not normally hamper the understanding of the text, comparable damage on a photograph would cover up information, and, on a magnetic tape, it could even render the tape unreadable. Seen, therefore, from the perspective of redundancy, audio­visual documents call for a higher degree of protection and security than written materials. Digital data can also be similarly endangered.

The modern electronic documents are to some extent insubstantial - many exist for part of the time only as a pulse of energy (for example, E-Mail messages passed over a telephone wire). They do, however, have certain safeguards built into them to help ensure the safe and complete arrival and storage of a message. They also have to be stored at some point on a physical carrier for later access.

One factor that most, if not all documents, have in common is their reliance on polymeric materials. The traditional materials of paper, parchment, leather, palm leaves etc. are all natural polymers. The newer media of tapes, discs and films rely on man-made polymers such as PVC and polyester. The rate of chemical de-composition of the various polymers varies greatly. Some will last - and have lasted - for millennia; others may struggle to survive for a decade.

All polymers decay. The decay cannot be stopped - but it can be slowed down by careful handling and favourable storage. It can also be greatly accelerated by careless handling and poor storage. All the storage conditions given in standards and other publications are for guidance. If the conditions are met, the decay does not stop. The figures quoted for temperature and humidity levels are a compromise between the rate of decay on the one hand and the costs of maintaining the conditions, of transfer and of conservation on the other. The conditions can be relaxed but at the expense of more rapid decay.

Format of the Guide

The various types of documents covered in this guide are divided into five groups:

Paper and Other Traditional Materials

Photographic and Micrographic Materials

Mechanical Carriers

Magnetic Materials

Optical Materials

There is an additional chapter covering the particular problems of preserving Electronic Publications, Electronic Documents and Virtual Information plus chapters giving some general preservation information and a glossary.

The Paper and Other Traditional Materials group include paper, parchment, leather and palm leaves. Seals are also included in this group. This is the oldest and largest group of documents.

The Photographic Materials group include all types of still photographic images - black and white and colour; negative and positive; transparency and print - on all types of carriers - paper, glass, cellulose and other materials and includes micrographs of all types.

The Mechanical Carriers group covers sound recordings on cylinders and discs.

The Magnetic Materials group include all forms of magnetic material - tapes, hard discs and floppy discs.

The Optical Materials group includes all laser read and written materials including CD-Audio, CD-ROM, CD-Recordable, magneto-optical disks and optical tape.

This guide is a compilation of contributions from a number of people, each expert in the preservation of a different type of document. Each field of expertise has developed its own terminology and, while there are many terms shared by all the disciplines, some are not. No attempt has been made to harmonise the terms used and so you will find different terms used in different chapters but meaning the same thing eg. user copy and access copy.

You will also find places where the topic has been covered in another chapter as well. Again, efforts have not been made to avoid this. Many readers will wish to read a chapter in isolation and this repetition will ensure that they receive all the information necessary for the understanding of the chapter.

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