EARS: An online bibliographic search and retrieval system based on ordered explosion

03c.5.45:3~87 53 Do c oa B 1987 Ptrgamon Journals Ltd.

EARS: AN ONLINE RETRIEVAL SYSTEM

BIBLIOGRAPHIC SEARCH AND BASED ON ORDERED EXPLOSION

R. RA_MESH* and COLIN G. DRURY~ *School of Llanagement and tDepartment of Industrial Engineering, State University of New York at Buffalo, Buffalo, NY 14260 (Rece~red 15 Aprll 1986; in revised form 1 December 1986) Abstract-Ergonomics Abstracts Retrieval System (EARS) is an online bibliographic information search and retrieval system using the hierarchical subject classification of the Ergonomics Absrracts. EARS is designed using an inverted file organization and is implemented on CDC-Cyber. The data base of abstracts is organized using a fixed-length record format, where each logical record corresponds to a variable number of fixedlength physical records. Accordingly, an index for the identification of physical records from the logical records is used. The data base is inverted on a three-level hierarchical classification scheme and postings files are used for data base inversion. The data base is accessed after selectively traversing a 4-layer structure of indexes and postings files. EARS provides facilities to perform combinations of searches, hmited searches, and certain editing functions. The system is currently used extensively by the Western New York Human Factors research community. The logical and physical designs of EARS, its interactive operational features, and its current expansions are described in this paper.

INTRODUCTION

This paper deals with the design and implementation of the Ergonomic Abstracts Retrieval System (EARS), an online bibliographic information storage and retrieval system. The system was set up for the North American Ergonomics Information Analysis Center at the State University of New York at Buffalo and serves as an information resource to the industry in the application of ergonomic principles and techniques. It provides the user with a quick, user-friendly, interactive facility to obtain literature references in particular ergonomic specializations. The information base for the system is the collection of Ergonomics Abstracts published quarterly by Taylor and Francis Limited of London. The system is written in PASCAL for use in CDC-Cyber environment. Numerous online search and retrieval systems are in use today. Prominent among these are MEDLARS (NLM), BRS, FAMULUS, EUREKA, DOBIS-LIBIS, ORBIT, and DIALOG. These systems are used for information retrieval from large data bases involving data base operations such as indexing, searching, and keywording; and creation of data sets for search and vocabulary files. The design and construction of the EARS data base and its online retrieval facility involve all these data base operations. Therefore, we briefly review the existing systems within the framework of EARS in the following discussion. MEDLARS [l-.5], or Medical Literature Analysis and Retrieval System, was originated by the National Library of Medicine (NLM). It is a data base of medical literature and is accessed through several online search and retrieval systems. This data base is indexed according to medical subject headings (commonly known as MeSH), as well as several other subheadings. MEDLINE is an online search and retrieval system developed by NLM for accessing information from MEDLARS. The system facilitates searching on author, title, source, and so on. The search strategies provide for combination searches and limited searches based on topic and time span. These searches employ Boolean techniques. Furthermore, the presence of hedges is a unique NLM feature that allows for storing and executing different types of searches. Bibliographic Retrieval Services (BRS) [2,5] is a bibliographic information company that supports an online search and retrieval system with the capability to handle the MEDLARS data base. Like NLM, BRS has the facility to search by author, author affiliation, 225

226

R R.&MESHand C. G. DRCR’I

source document, publication year, and publication type. A unique feature of the BRS system is the facility for “mapping” or preexplosion on the selected item. BRS also provides a free text searching facility. W’ords from the title, abstract, and index phrases are directly searchable free text. The specialized features of the BRS system are numerous and include the ability to nest different search statements. This system is typically an end-user search system, thus providing an easy search and retrieval facility to a wide range of users who are not necessarily skilled in the bibliographic search and retrieval processes. FAMULUS [6] is a collection of programs for creating and organizing files of information. The system has facilities for performing operations like indexing, searching, automatic keywording, and generation of vocabulary lists and KWIC indexes. EUREKA [7,8] is a minicomputer-based text retrieval system. It uses an inverted file organization. The data base comprises an index, the document text files, and the document vocabulary files. The vocabulary files contain complete word frequency statistics and are very suitable for interactive processin g. They provide users with a powerful tool for analyzing large amounts of retrieved information. DOBIS-LIBIS [9] is an online bibliographic information system for library use. It handles variable length records and keys, multiple keys and key types, multiword keys, large character sets, and other special requirements of a library data base. By utilizing documents and access point files (a form of inverted files), it fulfills authority file control requirements of libraries. ORBIT [5,10] is a search and retrieval system developed by the Systems Development Corporation (SDC). This system uses content classification codes with the facility for limiting the degree of search both in terms of topic and time span. Search with ORBIT usually proceeds by first identifying the concepts for search and retrieval, such as treatment, brain clamage, and so on. The concepts are then expanded and translated into more specific terms using the thesaurus in the system. ORBIT maintains a concept-wise taxonomy of search terms. It has numerous other capabilities as well. For instance, it provides for the storage of frequently used search strategies as hedges for subsequent use. Furthermore, it provides several print formats, where the user can selectively obtain specific information from the records retrieved from the data base. For example, the user can obtain the retrieved information in a standard form, or print just the accession number, title, and index terms and phrases, or print the full record, or employ specific tailored print formats. DIALOG [5,10] is a bibliographic search and retrieval system originally developed by Lockheed, which later grew into an independent subsidiary of Lockheed. It employs a thesaurus and content classification codes in the search and retrieval process. Searching with DIALOG proceeds similarly to ORBIT by identifying the concepts for search first and then successively exploding them into more specific ones. DIALOG provides for searches based on descriptor codes, content classification areas, identification of dissertations, specification of author, title and year information, and the use of an online thesaurus facility. It also provides numerous other search techniques, and introduced Knowledge Index in 1982, which is a cheaper, easier-to-use, after-hours version of DIALOG geared toward the end user. Like ORBIT, both DIALOG and Knowledge Index provide for limited searches based on topic and time span. Literature on online bibliographic search and retrieval is extensive. Harter [ 111presents the concepts and principles related to the online search and retrieval process. Harter [3] and Harter and Peters [12] discuss several strategies for online retrieval. Hawkins and Wagers [13] discuss the development of bibliographic search strategies. Levine [11] presents the principles underlying the design of data bases tailored to online retrieval, and Tenopir [ 1.51develops the characteristics of full-text data bases in bibliographic search. Other important features in this area include Burket et al. [ 161, Furlong [ 171, Hitchingham [18], Morgan [19], Raya and Soergel [20], and Sievert and Boyce [Zl]. A comprehensive survey of bibliographic data base systems and a history of the growth of the online search and retrieval methodology from 1970 till the present is given in Neufeld and Cornog [22]. All of the foregoing systems are characterized by varying degrees of complexity and sophistication. Most of them utilize inverted file organization and thesaurus/vocabulary lists. The searches are based on author, year, topic, and keywords. With the exception of

227

E.ARS

BRS, few facilitate ordered explosion on a selected topic. The current system is based on a unique exploitation of this hierarchical explosion feature. Further, the current system employs fixed-length format direct access data base files. The indexes representing the hierarchical classification scheme and the data base index are stored in the core memory at execution time. These features of EARS facilitate quick data base access and efficient utilization of disk space. The interactive system has been designed to guide the user systematically and progressively through the hierarchical classification scheme in the access and retrieval process. Our experience with this system in the last few years has shown this to be a quick, user-friendly, and interactive approach to the design of online bibliographic search and retrieval systems. The plan of the paper is as follows. Section 2 deals with the logical data base design aspects and Section 3 with the physical design. An overview of the actual, interactive usage is presented in section 4. Logical and physical design details of the current expansions to EARS are described in Section 5, and the conclusions are presented in Section 6. A stepby-step run through of the system highlighting its operational features is presented in the Appendix. LOGICAL

DESIGN

Taylor and Francis began the publication of Ergonomics Abstracts in 1969. The data base, presently, is composed of abstracts published from 1974 through 1980. We are currently in the process of expanding the data base to include the remaining years. Each of the over 35,000 references is composed of an access number, a title, the language it is written in if other than English, the author, publication information, and abstract content. The access number corresponds to the numbers of the abstract published in Ergonomics

Abstracts. The references are arranged in a trilevel, hierarchical index. There are 40 main headings at Level-l. Each of these headings has from 1 to 12 subheadings at Level-2. The second level is further subdivided from 0 to 17 elemental items at Level-3. Samples of the trilevel classification scheme used in the Ergonomics Absrracfs are shown in Fig. 1 and samples of the actual records are shown in Fig. 2. The record relationships for the EARS data base are as shown in Fig. 3. There is a one-to-many relationship between year to levels and within levels. There is a many-to-many

EQUIPMENT HAND

(LEVEL-l)

DESIGN TOOLS

IN RELATION IN RELATION IN RELATION hlACHINE

(LEVEL-2)

DESIGN TO ANTHROPO.METRY TO BODY XIECHANICS TO CONTROL REQUIRE>IENTS

(LEVEL-2)

DESIGN

Fig.

I. Hierarchical

(LEVEL-3) (LEVEL-3) (LEVEL-3)

subject

classificatton

scheme.

82563. Computer Commands in Restrtcted Natural Language: Some Aspects Experience. D. L. Scapin. [Human Factors, June. 1981, 23:3. 365-3751.

of Xlemory

and

In this experiment, tNo groups of subjects having different levels of experience with computers were tested to compare the learning and recall of computer command definitions that differed in context and redundancy and to study the effect of context change. The results show that inexperienced subjects have dtfferent requtrements than do more experienced subjects. The experienced group recalls more meanings than the inexperienced group but is more negatively influenced by the number of competing words than by contextual connotation. For the inexperienced subjects, particularly, tt appears that computer-ortenred words used as commands are better than more usual words. Besides, inexperienced subjects are more negattvely Influenced by context changes than are experienced subjects. Fi g. 2. Sample

Ergonomics

Abstracts

records.

R RAMESHand C. G. DRURY 9

YEAR

LEVEL-l

4

,,

LEVEL-2

t+---t)

LEVEL-3

Fig. 3. Record relarlonships.

relationship between the different levels and records. in any level under more than one heading/subheading.

PHYSICAL

Thus,

a particular

record can occur

DESIGK

The trilevel hierarchical classification system lends itself to a search strategy using the explosion of ordered index sets. To facilitate this process, each of the headings/subheadings in the different levels (Level-l, Level-2, Level-3) is assigned a category number. A sample assignment is shown in Fig. 4. Each position of the category number corresponds to a level. The number in the first position corresponds to a main heading in the first level. The number in the second position corresponds to a subheading in the second level. The number in the third position corresponds to an elemental subheading in the third level. Thus, the category number 20.1.2 identifies the abstracts dealing with hand tools design in relation to body mechanics under the main heading of equipment design. The category number 20.1.0 identifies all the abstracts dealing with hand tools design under the main heading of equipment design. The data base is accessed after selectively traversing a four-layer structure. A pictorial representation of this structure is shown in Fig. 5. The index-linkage diagram in Fig. 6 illustrates the actual retrieval process through an example. Index-A and Index-B represent the trilevel hierarchical subject classification scheme. The organization of the four-layer structure is described below. Index-A This is a 40 by 12 matrix representing the first two levels of the subject classification scheme. The rows represent the first level and the columns represent the second level of the scheme. Each element of this array is a pointer to a row of Index-B and represents the

EARS 20.0.0

EQUIPMENT

DESIGN

(LEVEL-l)

20.1 .O WAND TOOLS

DESIGN

20.1.1 IN RELATION 20. I .2 IN RELATION 20. i .3 fN RELATION 2052.0 MACHfNE

(LEVEL-2)

TO ANTHROPOhIETRY TO BODY ;MECWANICS TO CONTROL REQUiREMEWS

DESIGN

Fig. 1. Modified

(LEVEL-?) (LEVEL-3)
hierarchical

classification

scheme.

I Index-A

I

IfIbeX-C

( Index to the data base1

Data base

FIN;,2. Access to the data base.

1

130

R. RAMESH and C. G

Index-A (40x12 2 3

DRUR~

matrtx 1

Index -9 (480x

Fig. 6. Index linkage

M matrix )

diagram.

first entry at the third level of the particular classification. The row and column dimensions of this array correspond to the maximum number of items in the first and second levels. Index-B This is a 480 by LMmatrix. Each row in the array represents a unique subject classification in the trilevel system. Each column represents a year. The array element consists of two subfields. The first subfield is a key of the corresponding record in the appropriate postings file. The second subfield is the number of logical records (postings) indexed according to the index entry under consideration in that year. In the current implementation, iM corresponds to 7 years. With the addition of every year, the column dimension of the matrix will increase by one. The search and retrieval process begins with a specific subject in the hierarchical classification chosen by the user. Using the first two levels of the chosen subject classification,

E.-XRS

231

a cell of Index-A is accessed. For example, in Fig. 6, in retrieving records indexed by the classification 2.2.2, the cell in row 2 and column 2 of Index-A is accessed first. This cell points to row 22 of Index-B. This row corresponds to the classification 2.2.1. Since the hierarchical system is organized sequentially, row 23 is accessed to retrieve record information on the classification 2.22. A cell in index-B serves as a pointer to the set of records in the postings files that contain the key numbers of the records indexed according to the chosen classification in the logical data base. The logical keys of the data base records thus identified are used to determine their corresponding physical keys from Index-C.

The postings files sene as an interface between the indices representing the hierarchical classification (Index-A and Index-B) and Index-C which links the logical record key to the physical record key of the data base records. There are seven postings files, one for each year of the abstracts. The postings files are organized as direct access files with fixed-Iength physical records. Each logica record in a postings file corresponds to a unique subject classification. Each logical record consists of pointers to rows in Index-C. Each physical record consists of five integer fields. A logical record corresponds to a variable number of fixed-length physical records. The number of physical records for a given logical record is determined through a simple computation. For example, in Fig. 6, for the subject classification 2.2.1, there are eight data base records indexed in the first year of the abstracts. The physical records in the corresponding postings file start from record number 60 for this subject classification. The number of physical records to be retrieved is determined from the ceiling 18151, because there are five entries per physical record. In general, the function [number of records indexed)/51 is used for this purpose. Index-C

This is an N by M matrix, where N represents the m~imum of the number logical records in the M years and iM stands for the number of years. The fields in the postings records point to rows of this index. Corresponding to each posting in the postings file, a particular cell in Index-C provides the address for the physical location of the actual record in the data base. When the data base grows, M wil1 be increased by one with the addition of every new year, and N may have to be updated by increasing the number of rows accordingly. Data base The data base consists of seven direct access files and, one for each year of the abstracts. Each file consists of between 2,500 and 3,000 reference records. The logical records are variable in length and have access number, paper title, author/s, and citation as their fields. Using a direct access file with variable-length records on CDC-Cyber calls for certain special requirements. One has to specify the minimum and maximum lengths for the records. Based on these minimum and maximum record lengths, the Cyber Record Manager computes an average record length to determine storage requirements. This invariably leads of an inefficient use of disk space due to the unused cushion associated with almost every record. There is a further disadvantage of higher input/output time. To avoid this situation, fields within a record were delimited and each variable-length record was broken up into a variable number of fixed-length records, with 80 characters per record, and stored in the data base. Depending on the initial length of the record, the last of the fixed-length records may have fewer then 80 characters. Still, the overall result is an improved utilization of disk space. The splitting of the variable-length records into fixed-Iength records necessitates the creation of the data base index. If the variable-length record structure within the direct-access files had been used, no data base index would have been necessary. However, since the index is maintained entirely in the core, the retrieval time is not significant.

R. RAYESH and C. G. DRURY

232

OVERVIEW

To access and execute

the system,

OF ACTUAL

USAGE

a user simply

ATTACH, NAEIAC

has to type:

NAEIAC

with each statement followed by a carriage return. The system goes through a process that consists of five distinct stages. The system will provide lists of categories at Level-l and ask if the user wishes to search from the items. If the answer is yes, the user will be queried as to the items to be searched. Based on the selections at Level-l, the explosion/query/selection process is continued in a similar manner at Level-2. Based on the selections at Level-2, the explosion/query/selection process is continued at Level-3. Upon completion of the selection process at Level-3, the system provides a list of the number of reference items available for retrieval within each of the categories selected, for each of the 7 years (1974-1980). The user then specifies the year(s) of information to be retrieved. The requested information is then printed out. A complete step-by-step run through of the system and the corresponding output are presented in the Appendix. DESIGN

OF SYSTEM

EXPANSIONS

EARS is currently being expanded to include retrieval using a keyword thesaurus and chronological retrieval according to authors. This requires the addition of the following files to the current system: 1. Thesaurus index file 2. Thesaurus postings file 3. Author-chronological postings

file

The thesaurus index file is an alphabetized list of keywords and keyphrases related to the science of ergonomics. Each record in this file is identified by a keyword or keyphrase. The remaining fields in a record are pointers to the keywords and keyphrases related to its identifier. Thus, each record is linked to all its associated records explicitly. A conventional linked list organization of the index file is not feasible, since the relationships between the keywords are not necessarily transitive. The thesaurus postings files are organized according to the year of publication of the abstracts, as in the case of the hierarchical classification system. Each record in a postings file corresponds to a record in the index file. The logical organization of the thesaurus index file and the postings files is illustrated in Fig. 7. The thesaurus index search begins with the keywords provided by the user. If a usergiven word is identified, then all the available related keywords and keyphrases are obtained from its links in the index file. Furthermore, using the links of the words retrieved in this manner, additional keywords which may or may not be related to the user’s keyword can also be retrieved. Providing the user with these additional keywords will help him/her gain a better understanding of the available literature that may be related to his/her area of interest. This procedure is termed the first-level explosion of the thesaurus index. This process can be continued by successively traversing the links of the keywords obtained as above, leading to higher level explosions of the thesaurus index. As the levels of explosion increase, the relatedness of the keywords generated from the thesaurus to the user’s keyword is expected to decrease. Accordingly, the user can choose an appropriate level of explosion of the index and search the data base using the keywords retrieved from the index file. The keywords generated in this manner can be ordered according to a tree structure, with the user’s word as its root. This is illustrated in Fig. 8. After the keywords for abstract

Thesaurus

index

file

i --

Auditory

!

I

--

Perceptton w-it z

Oato base

Fig. 7. Logica

organization of the Thesaurus Search factiity.

Perception

Pictorial

Graphic

Analog Digital

Quolltatlve

Non Verbal Transmrsslon Equtpment

Fip. 8. An iflusrration of the ordered thesaurus explosions.

R. RAMESHand C. G. DRLTY

234

retrieval are chosen, using the postings files as in the hierarchical classification system, the appropriate records are retrieved from the data base. The author-chronological postings file is also designed on lines similar to that of the thesaurus postings file. This file is organized according to an alphabetized list of authors whose articles are included in the data base. The postings in each record represent the abstracts of articles written by an author, and are arranged in their chronologically ascending order. In summary, EARS is being expanded to provide the following search and retrieval facilities: 1. Search using user-defined keywords. This includes singular keyword searches as well as searches based on Boolean expression of keywords given by the user. 2. Search based on authors. searches that combine the use of the hierarchical classification system, 3. Integrated the keyword thesaurus, and the author index. In this case, a user can first select a classification, and then search either using his or her keywords or author names or a combination of both within the set of abstracts indexed by the classification. The system

organization

of the expanded

version

of EARS

is provided

in Fig. 9.

CONCLUSIONS

The Ergonomics Abstracts Retrieval System is currently set up for information retrieval using the hierarchical subject classification scheme. The system is currently being expanded to include retrieval using a keyword thesaurus and chronological retrieval ac-

(Data base [

Fig. 9. Logical organization of EARS.

EARS

235

cording to authors. The current size of the data base is over 15,000 physical record units (IPRU = 640 characters) of the CDC-Cyber. The postings files require about 750 PRUs. The programs and the indexes are stored in the core memory at execution time and their core requirements are very minimal. The programs are organized into a sequence of overlays and are executed in a successive manner. The programs are written in the University of Minnesota version of Pascal. The system is moderately CDC-dependent, as it exploits the internal structure and the 60-bit memory word organization of CDC computers. The system is quite transportable and requires limited conversion. Currently, we are working on an implementation of EARS on IBM13083. Currently, Boolean searches using the hierarchical classification scheme can be conducted, and this facility is being extended to the thesaurus and the author index as well. Furthermore, integrated searches using the three indexing facilities are also being incorporated. EARS is currently used by researchers in the human factors community and its use is becoming extensive. Access to EARS is available by contacting the Department of Industrial Engineering, State University of New York at Buffalo. Users are reporting their satisfaction with its search facilities, the depth and scope of its data base, and the user-friendliness of its interactive facility. Demand for library searches using EARS has been overwhelming. The expanded version is expected to tremendously facilitate research in human factors.

REFERENCES

I.

2. 3. 4. 5. 6. 7. 8. 9. 10 11. 12 13 14. 15. 16. 17. 18. 19. 20. 21. 22.

Bachrach, C. A.: Charen, T. Selection of MEDLINE contents, the development of its thesaurus and the indexing process. hIed. Inf., 3:237-254; 1978.. Burrows, S.; Kyle, S. Searchmg MEDLARS file on NLM and BRS. Bull. Med. Libr. Assoc. 67:15-24, 1979 Harter, S. P Online informanon retrieval-concepts, principles and techniques. Orlando, FL: Academic Press; 1986. blEDLARS Indexing manual (Parts I and II). National Technical Information Service, U.S. Department of Commerce, Springfield, VA; 1977. Technical no[es: MEDLARS indexing instructions: supplements VII, VIII and IX (BRS, DIALOG and ORBIT). National Technical Information Service, U.S. Department of Commerce, Springfield, VA; 1982. Hockey, S. hl. Famulus on the 1906A. Oxford, UK: Oxford University Computing Service; 1978. Burket, T. G.; Emrath, P. User’s guide to EUREKA and EURUP. Report 79-956. Champagne-Urbana, IL: Department of Computer Science, University of Illinois; 1979. Rinewalt, J. R. Evaluation of selected features of the EUREKA full-text information retrieval system. Reporr 76-823, Champagne-Urbana, IL: Department of Computer Science, University of Illinois; 1976. McAllister, A. S.; McAllister, C. A. design for an online bibliographich database-the DOBIS-LIBIS database. Info. Process. Manag. 17:27-38; 1981. Weiss, I. Evaluation of ORBIT and DIALOG using six data bases. Spec. Libr. 12574-581; 1976. Harter, S. P. On-line searching styles: an exploratory study. College Res. Libr. 45:248-250; 1984. Harter. S. P.: Peters. A. R. Heuristics for onhne information retrieval: a typology and preliminary listing. Online Rev. 4:407-424; 1985. Hawkins, D. T.; Wagers, R. Online bibliographic search strategy development. Onhne 6:12-19; May 1982. Levine, G. R. Developing databases for online information retrieval. Online Rev. 5: 109-120; 1981. Tenopir. C. Full-text databases. Annual Rev. Info. Sci. Technol. 10:215-246; 1984. Burket. T. G.: Emrath. P.: Kuck. D. J. The use of vocabulary files for on-line Information retrieval Info. Proces;. illan&. 15:281-2i9. 19j9. Furlong, E. J. index access to on-line records: an operations view. J. Libr. Automat. 11:223-238; 1978. Hitchmeham. E. A survey of database use at the reference desk. Online 8:44-50; .&larch 1984. Morgan, J. K: Description-of an experimental on-hne minicomputer-based information retrieval system. Report 79-779. Champagne-Urbana, IL: Department of Computer Science, University of Illinois; 1976. Raya, F.; Soergel, D. Factors affecting online bibliographic retrieval: a conceptual framework for research. J. Am. Sot. Info. Sci. 34:163-180; 1983. Sieberr, ;LI. E ; Boyce, B. R. Hedge trimming and resurrection of the controlled vocabulary. Online Rev. 7:489-494; 1983. Neufeld, Xl. L.; Cornog, M. Database history: from dinosaurs to compact discs. J. Am. Sot. Info. Sci. 37:183-190: 1986.

APPENDIX

Following

is a step-by-step

run through

Messages will appear introducing be prompted to enter a carriage

of the system.

you to the system and explaining return to continue.

the search methodology.

YOU

will

R. RAILIESH and C. G. DRL.RY

236

(LINES BEGINNING WITH << REPRESENT WHAT YOU WILL SEE ON THE CRT SCREEN WHEN USING EARS) << items There << These << Enter CC

on the first level: are 40 items on the first levei. wiIi be presented in four pages of ten items each. CR to continue

Items I-10 will be presented. Examine the list and decide whether you will select any of the items for a reference search. << Do you wish to search from the above items? (Y/N) Enter a Y if you wish to search any of the items or an X if you do not wish to search these items. A NO answer will result in the listing of the next page of ten items. A YES will result in the prompt: cc Enter the item-numbers of your selections, one item per line << Terminate with a in the last line. Enter the item-number of your selection. Enter a carriage return. Continue until no further selections are desired from this page. Enter a CR to continue. The next page of items is then displayed. Example: 1.

10: << Do you wish to search? (Y/N) 11.

<< << << << cc

20: Do you wish to search (Y/N) ?20 Enter the item numbers . . . ?20 ? 21.

<<: << << << <<

30: Do you wish to search? (Y/N) ?Y Enter the item numbers . . . ?21 ? 31.

<< << << <<

40: Do you wish to search? (Y/N} ?N You have chosen the following items in the first level: 20 21

The system proceeds to explore the second level of the items you have chosen. << Category selection: 20 << Category Description: 20. Equipment design << Do you wish to search for any general references in this category? (Y/N) There may be some genera1 references associated with equipment design. Decide whether YOU wish to search the general references on this topic, Enter Y or N according to your decision.

EARS The system will display all second

level headings

237

belonging

to the first level item you have chosen.

<<
Items on the second level: 1. Hand tool design 2. IMachine design Do you wish to search from the above items? (Y/N) ? Y Enter the item-numbers of your selections . . . << ? 2

The system will not investigate

the third level of the item-numbers

you have selected.

<< Category selection: 20.2 Category description: Level 1: 2. Machine design Do you wish to search for any general references in this category? (Y/N) ?Y Items on the third level. 1. In relation to anthropometry. 2. In relation to body mechanics. 3. In relation to control requirements. Do you wish to search from the above items? (Y/N) ?Y Enter the item-numbers of your selections . . . ?2 3

<< << << << << << << << << << << << << << <<

At this point the system goes back and explores the second and third levels of any remaining selections. In this case, it is category 21. After all levels of all selections have been explored, the system lists the number of references per year that are available for retrieval in the categories you have selected. << << << << << << << <<

Category selections: 20.2 Category description: Level 1: 20. Equipment design Level 2: 2. Machine design Level 3: 2. In relation to body mechanics.

<< Year: 1974 1975 1976 1977 1978 1979 1980 5 0 1 0 3 10 8 << Enter the number of years you wish to retrieve.

If you do not wish to retrieve,

then enter “0”.

<< Enter the last two digits of the years: << Example: 71, 75, 76, etc. << Enter number << ? 1 ?

of years you wish to search.

<< Enter the last two digits of the years you have chosen << ? 80 << ? This display and response The You then copy

of the number

per year is repeated

for all selected categories.

list of references that you have selected will then be written onto the local file called ‘Tape4’. may rewind Tape4 and copy it on the terminal screen to take a look at it immediately. You may send the file ‘Tape4’ to the appropriate satellite site of the computer center to receive a hard of the output.

Here is a sample output.

<< List of references << << << << << <<

of references

to search.

Category: 20.0.0 Category description Level 1: 20. Equipment design Abstract year: 1974 Number of references:

1

R. RAYESH and

238

C. G. DRLRY

<< *a2078 << Safety in fork lift trucks

(sicherheit

beim staplereinsatz

.).

<< (in German.) << W. Abt and H. Laumann. << [IManagement zeitschrift, 1981, 50/j,

241-245.1

<< << << << << << <<

Category: 20.2.0 Category description Level 1: 20. Equipment design 2. Machine design Abstract year: 1980 Number of references:

<< << << <<

*82323 Improvement of transportation in hospitals. (in Japanese.) T. Takahaski. [Japanese Journal of Ergonomics, June 1979, 1513, ill-115.1

<< << << << << << << << << << <<

Category: 20.2.2 Category description: Level 1: 20. Equipment design Level 2: 2. Machine design Level 3: Abstract year: 1980 Abstract year: 1980 Number of references: *82156

1

1

<< Hand movement times and machine guarding. << B. T. Davies and B. Mebarki << [Ergonomics, May 1981, 2315, 387-391.1 General references are given in the categories with a zero in the second and/or third position category number. This is illustrated by the first two references given in the sample output.

of the

If there were no references for a certain year but you choose that year anyway from which to retrieve references, the output will appear in the following way: << Abstract << Number

year: 1980 of references:

The printout

then just goes on to the next retrieval

0 selection.