31DESIGNING AN ONLINEPUBLIC ACCESSCATALOGUE
Nathalie Nadia Mitev, Gillian
M Venner and Stephen Walker

Library and Information Research Report 39|Bjy
The British Library

WQ

British Library Cataloguing in Publication DataMitev, Nathalie Nadia
Designing an online public access catalogue:
Okapi, a catalogue on a local area network.
(Library and information research reports,
ISSN 0263-1709:39)
1. Catalogs, On-line
I. Title
II. Venner, Gillian M.
III. Walker, Stephen
IV. Series
025.313
Z699
ISBN 0-7123-3058-5

v

DESIGNING AN ONLINEPUBLIC ACCESSCATALOGUE:Okapi, a catalogue on alocal area network
NATHALIE NADIA MITEV, GILLIAN M VENNER
STEPHEN WALKER

Library and Information Research Report 39

Abstract
Designing an online public access catalogue [OPAC]: Okapi, a catalogue on a
local area network [LAN] is the final report of a two-year research project''Microprocessor networking in libraries" which was funded by theBritish Library and the Department of Trade and Industry, and based at
the Polytechnic of Central London.
The aim was to produce an OPAC on a LAN, that would be readily usable
without training or experience, without sacrificing effectiveness or being
tedious for experienced users.
The result was a functioning prototype OPAC called Okapi, which has anumber of distinctive features: use is eased by coloured keys and a lack ofjargon; the system uses search decision trees to select a suitable action ateach stage of a search, and it performs automatic Boolean and hyperBoolean functions where appropriate. The OPAC was installed andevaluated in one of the Polytechnic site libraries.
There is a full description of Okapi under the headings: source file:indexing; search functions; user interaction and evaluation. There arealso general discussions of these topics, and chapters on OPACs ingeneral, LANs, and recommendations for future research.
Library and Information Research Reports are published by the British
Library and distributed by the British Library Publications Sales Unit,
Boston Spa, Wetherby, West Yorkshire LS23 7BQ.
© The British Library Board 1985

ISBN 0 7123 3058 5
I S S N 0263 1709
T h e opinions expressed in this report are those of the authors andnot necessarily those of the British Library.
Typeset in Great Britain by SB Datagraphics Ltd, Colchester and printedby William Clowes (Beccles) Ltd, Beccles.

VPrefaceThis report is primarily about the design and use of online public accesscatalogues (OPACs). It describes the application of a study of existing
online catalogues, and of research in information retrieval and otherfields, to the design, construction and testing of a prototype experimental
OP AC (called Okapi). The prototype catalogue was designed to operate
within a local area network (LAN), although there is little in this report,
or in Okapi, which is specific to the LAN environment.
The intended readership includes library management and technicalservices personnel, students of library and information science, and thoseconcerned with interactive computer systems, particularly with systems
intended for untrained and non-dedicated users.
Most of the report assumes little prior knowledge of library automation orof computing in general, but there are a few sections which require more
specialised knowledge.
We wish to thank all those who have helped us during the course of theproject. In particular we wish to thank Neil McLean and Mel Collier(Head and Deputy Head of Library Services, Polytechnic of Central
London) for their constant support, and Paul Baxter and Maureen
Grieves of the British Library Research and Development Department,
who have given so much time to the project.
Other Polytechnic staff without whom the work would scarcely havebeen possible are Winifred Abbott (Technical Services Librarian) andthe cataloguing staff — particularly Penny Pope and Helen Chapman —for endless help on cataloguing matters and the use of MARC; Maura
Coghlan and her staff in the Riding House Street Library for providing
facilities for us to install and test the catalogue with real users; and Dave
Roberts (Head of Computer Services) for access to computing facilities.
Our colleagues in the Library Technology Centre, Pat Manson and Mary
Rowbottom, gave advice and encouragement on many occasions.

Preface

VI

Outside the Polytechnic, we are particularly grateful to the following
people: Philip Bryant and Alan Seal of the Centre for Catalogue Research
for many stimulating discussions on the use of catalogues in general andon OPACs in particular; Linda Reynolds for help with screen layouts andwith the design of evaluation procedures; Charles Hildreth of OCLC forencouragement and for having written the best book on OPACs [1]; thestaff of Nestar Systems (suppliers of the hardware) — particularly
Railton Frith (Technical Support Manager); Alan Hopkinson for thebenefit of his encyclopaedic knowledge of cataloguing and of bibliographic exchange formats; and Margaret Slater of Aslib for her valuableadvice.
Finally, there were the several hundred people — Polytechnic students
and staff, professionals in various fields, conference delegates and passers
by, friends and relations of the project team — who acted as guinea pigs
by being persuaded to sit down in front of computer terminals, were told
"Just use it!", and were observed and questioned. These individually
unacknowledged collaborators made countless constructive suggestions,many of which have been incorporated in the prototype OP AC describedin this report.
May 1985

NNMGMVSW

Reference1

Hildreth C R. Online public access catalogs: the user interface. OCLC,
1982.

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Contents
List of figuresxii

List of tables

xiii

1
1.1
1.2
1.3
1.4

Background, history and aims
The project proposal
Staffing
History of the project
Aims of the project

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62
2.1

Online public access catalogues
Sources of information on OPACs
2.1.1 Existing OPACs
2.1.2 Written sources
OPACs as IR systems
2.2.1 Coverage and source
2.2.2 Users and usability
From conventional catalogues to OPACs
Types of OP AC currently in use
2.4.1 First generation OPACs
2.4.2 Second generation OPACs
2.4.3 The third generation
2.4.4 The National Library of Medicine ( N L M ) CITE OP AC
Types of catalogue search
2.5.1 Specific item searching
2.5.2 Subject searching
User interaction with OPACs
2.6.1 User attitudes and behaviour
2.6.2 OP AC input from users
2.6.3 OPAC output
OPAC design
2.7.1 OPAC components
2.7.2 The design of Okapi

77789910101112131415161717181819202020
21

2.2
2.3
2.4

2.5
2.6

2.7

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Contents

3
3.1
3.2

Local area networks
Types of LAN
LAN or multi-user minicomputer?
3.2.1 Relative cost
3.2.2 Performance considerations: LAN advantages
3.2.3 Performance considerations: shared processor advantages
3.3 The project LANs
3.3.1 General description and cost
3.3.2 Performance
3.3.3 Reliability
3.3.4 Some technical information on the PLAN 4000 LAN
3.4 Data security
3.5 The design of applications software for LANs

252628282830303032343435364
4.1
4.2
4.3

Creation of Okapi source file
Machine-readable catalogue and choice of project test site
Selection of fields from the MARC record
Discussion of MARC fields omitted and other problems
4.3.1 Statements of responsibility
4.3.2 MARC fields omitted
4.3.3 Records with analytical entries
4.3.4 Other problems of creating a MARC subset
4.4 The Okapi record
4.5 Creation of Okapi file from MARC file
4.5.1 Creation of Okapi record from MARC record
4.5.2 Transfer of data to PLAN network
4.5.3 Final Okapi file creation on PLAN
4.6 File size, mean record length and other statistics
4.7 Order of records in the file and on screen
4.8 File updating and maintenance

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5
5.1
5.2

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5.3

Access to catalogue files: indexing
Introduction and guide to the chapter
OPAC index contents
5.2.1 Access points — the sources of index keys
5.2.2 Data types
5.2.3 Okapi index contentsFiling order and the display of indexes
5.3.1 Browsing and index order
5.3.2 The readability of index displays

ContentsIX

5.3.3 Character coding and filing order in indexes
5.3.4 Filing order and display of the Okapi index
The construction of indexes for bibliographic records
5.4.1 Personal names
5.4.2 Corporate and conference names

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5.4.3 Titles

65

5.4.4 Subject headings
Stop lists and authority
files
5.5.1 Stop lists
5.5.2 Authority
files
Index storage and access5.6.1 Methods of storage
5.6.2 Postings lists
5.6.3 Searching an index
5.6.4 The representation of data in indexes
5.6.5 One index or several indexes?
The Okapi index: storage, access and construction
5.7.1 Summary
5.7.2 Choice of index structure for Okapi
5.7.3 The secondary index
5.7.4 The primary index
5.7.5 Postings and beasts
5.7.6 Construction of the Okapi index

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81

6
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9

Search functions and search trees
String comparison
Possible results of an index search
Conditional searching
Booleans
Hyper-Booleans
Computational aspects
String searching
Search trees
Functions not implemented and reasons why8787888989
90
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96

7
7.1
7.2
7.3

User interaction designIntroduction
Users' reactions to previous online catalogues
Previous OP AC designs and their user interfaces
7.3.1 IR aspects

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104

5.4

5.5
5.6

5.7

ContentsX

7.3.2 Dialogue aspects
General approach to Okapi user interaction
7.4.1 How many interaction levels?
7.4.2 How to offer search types
7.4.3 Automatic features: behind the screen...
7.5 Structure and description of Okapi dialogue
7.5.1 User input* 7.5.2 Action by Okapi
7.5.3 Okapi displays

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8
8.1Okapi in use
Introduction
8.1.1 Brief literature review
8.1.2 What can be evaluated and why?
Methodology
8.2.1 Automatic logging
8.2.2 Observation and structured interviews
Structured interview results
8.3.1 Users' background and experience
8.3.2 Users' opinions of Okapi
8.3.3 Questions about their search
Analysis of user sessions
8.4.1 Session length, types of searches, search states
8.4.2 Search failures
8.4.3 Use of keys, spelling and input mistakes
Logging results

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Conclusions and recommendations
Summary of results of the project
OPACs — advantages and disadvantages
LANs and library automation
Some conclusions and recommendations for research anddevelopment
9.4.1 On the enhancement of subject searching in OPACs
9.4.2 On data input by the user: spelling and keyboarding
9.4.3 On OP AC output
9.4.4 On user interaction in general
9.4.5 On bibliographic files for OPACs
9.4.6 On the evaluation of OPACs and the study of their use
9.5 Concluding remarks

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161

7.4

8.2
8.3

8.4

8.5
9
9.1
9.2
9.3
9.4

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ContentsXIAppendices
12
3
4
5
6

7
8
9

MARC field selection criteria
Subnelds used from selected MARC fields
Okapi record format
Special characters used in the Okapi record
General comments received about Okapi
Results of 70 interviews
1 Students' background and experience
2 Questions about Okapi
3 Questions about their search
4 Some cross-tabulation
Analysis of 96 user sessions
Okapi logging results
Annotated and edited extract from the log of an Okapi station

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199
201
202
203
204
208
209

References

211

Glossary

221

Index

232

Other reports

251

Xll

List of figures
3.1

LAN diagram

33

4.1

Complete MARC to Okapi example

51

6.1

Title only search tree95

7.1
Subject search in LCS (Ohio State University)
7.2
Main menu in Bibliotech (Advanced Management System)
7.3
User asks for help in Datalib
7.4
Okapi introductory screen
7.5
Okapi first menu
7.6
Okapi first menu with help
7.7Okapi keyboard help
7.8
Okapi overall view of specific item input
7.9
Okapi specific book help (1)7.10 Okapi specific book help (2)7.11 Okapi title input
7.12 Okapi author input
7.13 Okapi subject search input
7.14 Okapi subject search help (1)7.15 Okapi subject search help (2)7.16 Okapi search: author only (match)
7.17 Okapi search: author only (no match)
7.18 Okapi search: author only (AND)7.19 Okapi search: title only (match)
7.20 Okapi search: title only (partial match)
7.21 Okapi search: title and author
7.22 Okapi search: subject (AND)7.23 Okapi search: subject (hyper-OR)
7.24 Okapi author index display
7.25 Okapi title index display
7.26 Okapi brief record display
7.27 Okapi full record display

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List of tables
5.1
5.2
5.3
5.4

The most frequent terms in a file of 30,081 MARC records
Analysis of index terms by type of key
Index size and term occurrence statistics
The most frequent initial tetragrams

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7.1
7.2
7.3

Summary of the first two generations of OPACs
Two levels of interaction
Automatic displays

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