Thesaurus basics
- What is the UK Archival Thesaurus?
- Why is a thesaurus useful?
- How does a thesaurus work?
- What standards are there?
- How are terms edited?
What is the UK Archival Thesaurus?
The UK Archival Thesaurus (UKAT) is a structured wordlist which brings together the various diverse terminologies currently in use within the archival community for subject indexing. The Thesaurus has taken the UNESCO Thesaurus as its starting point, and has incorporated terms from other wordlists and structured vocabularies (such as Library of Congress Subject Headings), as well as specialized terminology from a variety of UK archive projects, such as A2A and AIM25. By standardizing the terms in use, UKAT will assist archivists in their indexing work, and will help archive users to retrieve information about archives. For further information about the project, see About UKAT.
Why is a thesaurus useful?
Unlike a wordlist, a thesaurus groups terms with a similar theme together and defines relationships between them. This allows the user to find all the terms relating to a particular subject quickly and easily. A thesaurus is a dynamic tool, which can be developed by the addition, amendment and deletion of terms, relationships or hierarchies as dictated by the needs of the user community.
How does a thesaurus work?
A thesaurus is primarily concerned with suggesting preferred terms for use in describing 'concepts', in this case archive subjects, and establishing relationships between them. The three main relationships within a thesaurus are:
In addition, each term should preferably be provided with a scope note, which is used to define the term. UKAT also has a higher level structure consisting of fields of knowledge and microthesauri.
As in many thesauri, the information in UKAT is presented in essentially two ways: via the main term display, and via the hierarchical display (also referred to as the 'hierarchical browsing'). The main term display shows the full information for a term. It can be accessed by clicking on the link from each term in the A-Z lists of terms, the hierarchical display or the results of searches. The hierarchical display only shows broader and narrower term relationships, and the relationships between preferred terms, microthesauri and fields of knowledge. For further information, see Main term display, Browsing A-Z, and Browsing by hierarchy.
Equivalence relationship
In everyday language, it is quite common to find a situation where there are many different words to describe the same thing. The equivalence relationship allows the creator of a thesaurus to specify which of these terms should be used for indexing. This term is referred to as the preferred term. The other terms (known as non-preferred terms) will be included in the thesaurus, but only as guides to direct the user to the preferred term. The benefit of this is that only one term needs to be used for indexing and retrieval.
This relationship is usually depicted using the conventions USE and Used For (UF). For example, here 'Serial' is the preferred term for 'Magazine':
Serial Used For Magazine Magazine USE Serial
This tells us that 'Serial' has been used in the place of the term 'Magazine'.
In UKAT, non-preferred terms are not displayed when you browse the Thesaurus by hierarchy. They appear in the A-Z lists of terms and in the results of searches. In these lists, non-preferred terms appear as guide terms, directing you to use their preferred terms (e.g. 'Careers USE Occupations'). In some cases, a non-preferred term may direct you to use more than one preferred term, e.g.:
Womens education USE Education, Women
Like preferred terms, each non-preferred term will link to its main display page, which provides further information about the term. See the Main term display help page for further information.
Hierarchical relationship
A thesaurus allows terms related to a similar subject to be grouped together. This is usually in the form of a hierarchical display, where the term at the top of the hierarchy is the broadest in meaning, with the terms further down the hierarchy becoming more specific or narrower in meaning. Each of the more specific terms must be 'a kind of' the broader term. For instance, in a hierarchy where the broadest term is 'Rodents' you might have the narrower terms of 'Rats' and 'Mice'. This relationship is governed by a simple rule known as the 'all and some' rule. This states that all of the narrower terms in a hierarchy must be 'a kind of' the term above. So all 'Rats' are 'a kind of' 'Rodents'. However only some 'Rodents' are 'Rats'.
If we had a hierarchy of 'Pests', the 'all and some' rule would not apply, since although some 'Pests' are 'Rats', only some 'Rats' are 'Pests'. Therefore, in a general thesaurus this cannot be a true hierarchy. Of course, in a thesaurus of pest control it would be acceptable.
In UKAT, the hierarchical relationship is displayed in two ways:
- (1) In the hierarchical browsing, it takes the form of an indented list within each microthesaurus. The broadest terms are at the top of the list, and the narrower terms are increasingly indented further down. Only preferred terms are included. See Browsing by hierarchy for further information.
- (2) The main term display for preferred terms indicates the term's immediate broader terms and immediate narrower terms, for each microthesaurus in which the term is placed. The full hierarchy can be seen via the hierarchical browsing. See the Main term display help page for further details.
Associative relationship
This relationship allows preferred terms in a thesaurus to be associated, or related, to terms which are not in the same hierarchy but may be of interest to the user. Using the previous example, we could create an associative relationship between the terms 'Rats' and 'Pests'.
In UKAT, related terms are displayed in the main term display for preferred terms (see Main term display for further information).
Scope note
The scope note is not only used to define the term, but can also give directions as to how a term should be used. For instance, the scope note for 'Rats', as well as explaining what rats are, might include the following statement: 'For rats kept as pets use Pet rats'.
In UKAT, scope notes appear in main term display pages for preferred and non-preferred terms (see Main term display for further information).
Fields of knowledge and microthesauri
UKAT, like the UNESCO Thesaurus, is divided into fields of knowledge. The fields of knowledge which UKAT has inherited from UNESCO are:
- 1. Education
- 2. Science
- 3. Culture
- 4. Social and human science
- 5. Information and communication
- 6. Politics, law and economics
The UNESCO Thesaurus' seventh field of knowledge ('Countries and country groupings') has not been used by UKAT. However, to avoid creating difficulties for archives which have used this section, no other field of knowledge has been assigned in its place. UKAT has created one additional field of knowledge (numbered 8) for events, periods and roles.
Each field of knowledge is divided into microthesauri. These are groupings of terms which are conceptually related by subject. For instance, in the 'Education' field of knowledge there are microthesauri covering 'Educational planning' and 'Basic and general study subjects'. The microthesaurus to which a term belongs can be seen in the main term display. Each microthesaurus is preceded by a three digit numeric code. The number before the decimal point indicates the relevant field of knowledge. The codes for the two previous examples are 1.15 (for 'Educational planning'), and 1.45 for 'Basic and general study subjects'.
When browsing UKAT by hierarchy, you can move progressively downwards from the fields of knowledge, to the microthesauri within a field of knowledge, and then to the preferred terms in a microthesaurus (see Browsing by hierarchy). When searching UKAT, it is possible to refine the search by using the relevant field of knowledge and/or microthesaurus (see Searching UKAT).
What standards are there?
The main English language standards for thesauri like UKAT which are not multilingual are:
- (1) British Standard Guide to Establishment and Development of Monolingual Thesauri (BS 5723: 1987; ISO 2788-1986). Published by the British Standards Institution, this is the UK implementation of a standard issued by the International Organization for Standardization.
- (2) Guidelines for the Construction, Format, and Management of Monolingual Thesauri (ANSI/NISO Z39.19-2003), developed by the US National Information Standards Organisation and approved by the American National Standards Institute.
How are terms edited?
Terms submitted to UKAT are edited using a construction and editing methodology which has been approved by the project's Advisory Panel. The report setting out this methodology can be downloaded from the Downloads page. It is substantially based on BS 5723 (see What standards are there?), and on recognised authorities on thesaurus construction.
Editing is a multi-stage process which determines where terms will appear on the UKAT website. In order to maintain the distinction between the edited and unedited parts of UKAT, and between terms which have been accepted and rejected, unedited terms are limited to the Candidate terms pages; while rejected terms will only appear in the pages of Rejected terms. The Main thesaurus: browse A-Z and Browse by hierarchy pages only display terms whose status is 'pending' (indicating that the term has been edited and is awaiting incorporation following a period of consultation) or 'approved' (edited and fully incorporated). It is recommended that only pending and approved terms should be used for indexing purposes. Terms can be searched by status (and regardless of status) using the Advanced search form: see Searching UKAT for further details.
For further information on the editing process and how to submit terms to UKAT, see our Guidelines for contributors.