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A thesaurus is used to standardise terminology, allowing the recording of information in a consistent and retrievable way. In a thesaurus, 'concepts' (such as types of objects, ideas or actions) are grouped into hierarchies and linked to related concepts. Each concept is labelled by a 'preferred term', and may be referred to from alternative 'non-preferred' terms also used to identify that concept (for example, coach USE carriage). The hierarchical structure allows objects or documents to be indexed and searched at a general or specific level, as appropriate. For example, a search for 'rolling stock' might locate a book about carriages and wagons in general and also a specific object indexed under the more precise term 'carriage'.
A thesaurus can be developed by the addition, amendment and deletion of terms, relationships between terms and/or hierarchies as dictated by users needs.
By standardising information that is entered onto a database it is easier to search records and retrieve the required output. The use of a thesaurus facilitates the retrieval of information created by someone else. It also allows users to access and retrieve data not only within specific information systems but also across a range of information systems operating within a single organisation, or across many organisations.
The simplest way to ensure that the information is consistent is to use a word list. This is merely an alphabetical list of accepted terms used to control the information recorded in a specific field within a database. However, a word list does not allow the user to create hierarchical relationships between the terms. Using a thesaurus structure, expanding abbreviations and removing punctuation, can greatly aid the indexing and retrieving of object types. It also reduces the number of searches required to retrieve information from a database.
Because the thesaurus can also include all the non-preferred synonyms, users need not pick the 'correct' one when making a search. If the database software can access the thesaurus, the user can enter the word of their choice and the computer will then retrieve all records indexed with the corresponding 'preferred' term.
This thesaurus is primarily concerned with suggesting preferred terms for use in indexing railway objects and establishing relationships between them. Complexes comprising many objects such as stations, depots or even complete railway systems are included.
The scope is limited to objects specific to railways in Britain or railway equipment manufactured in Britain. As a result some terms have been omitted, including terms of exclusively American usage and general terms for objects used by other industries as well as railways. For example, railway companies were heavily involved in catering and maritime operations but most of the artefacts connected with these enterprises were no different to those used outside the railway industry. Other thesauri such as the Art and Architecture Thesaurus, Maritime Craft Types, RCHME/English Heritage Thesaurus of Monument Types, etc. should provide a suitable framework for categorising these items and can be utilised in parallel with the Railway Object Name Thesaurus.
Occasionally non-railway terms have been included where they are necessary to link very specific railway items to the higher levels. For example, the non-specific term drawing instrument is provided in order to link railway-specific instruments such as rail scale and railway curve to the railway manufacturing and maintenance equipment section of the railway Tools and equipment hierarchy. Other terms commonly used outside the railway industry are included when they are inextricably linked with the core activities of rail transportation (e.g. buffer, firebox, tyre, etc.).
Foreign and regional terms are also excluded unless they have passed into common English usage or provide the sole description for an object type (for example, capuchon). Where a regional term does not fulfil these criteria, the user will be guided to a term that is more widely used and is synonymous with the regional term (e.g. dillyway use tramway).
Other attributes used to describe railway objects, such as period and materials, are generally excluded from this thesaurus, as they have an integrity of their own and are generally recorded separately, especially within computerised databases.
Again there are exceptions. Terms that describe the form of the object rather than, or in addition to, the function have occasionally been included where they are considered useful or necessary. For example, wooden rail and iron rail have been included as they represent totally different phases in railway development and should be differentiated from each other through the object name used.
Slightly more abstract terms that cannot be said to apply to discrete objects have occasionally been included where it is felt that this would be helpful when cataloguing photographs. For example, terms for areas such as bank foot and summit are included, as are running lines (e.g. slow line), etc.
Inevitably the first edition of a work of this complexity has many omissions, particularly in certain areas (modern traction for example). These deficiencies will be addressed in future editions. Had publication been delayed until the gaps had been filled it might never have appeared at all.
Whilst it is hoped that future editions will become increasingly comprehensive, it is accepted that it would be both impossible and undesirable to include every conceivable name for every type of experimental or one-off item used on Britain's railways or exported by British manufacturers. Some representative examples of such 'oddities' have been included. It is hoped that users can follow a similar logic to slot in others as required within their individual collection catalogues. Meanwhile, efforts will be concentrated on adding terms more likely to be encountered by the average user.
This edition lists a total of 4,015 terms comprising:
| Preferred terms | 3,165 | ||
| Non-preferred terms | 372 | ||
| Class terms, Grouping terms and Facet indicators | 478 |
The structure of this thesaurus is based on guidelines given in BS5723/ISO2788 Guidelines for the Establishment and Development of Monolingual Thesauri (British Standards Institution, 1987) and Thesaurus Construction and Use (Aitchinson, Gilchrist and Bawden, 1997). It groups terms by class rather than the broadest noun term (Top Term). It was felt that it would be useful to group terms under broad classes thereby linking types of object in a way that, in general, reflects the organisational structure of the railway industry (for example, objects normally installed and maintained by the Signalling and Telegraph Department are grouped under the Control and communications class whilst those for which the Permanent Way Department are responsible are grouped under Track and track components).
The broadest noun term in each hierarchy is identified in some thesauri as the Top Term. This thesaurus does not explicitly identify Top Terms as the classes are not part of the hierarchy and the highest level terms within the classes are often grouping terms which are not preferred indexing terms and therefore do not strictly qualify as Top Terms.
The cultural heritage sector tends to use the singular instead of plural form for naming objects and that is why mda thesauri use the singular, unless it affects the meaning of the term. This is allowed for in BS5723/ISO2788. Plural equivalents are also available to facilitate future cross-searching encompassing databases from sectors that have adopted the plural form. However, in order to reduce the bulk of this printed version, only those irregular plurals not formed by simply adding an 's' to the end of the singular form are explicitly listed. Digitised versions will include all plural equivalents.
Removing punctuation such as apostrophes and hyphens can greatly aid indexing and retrieval and this practice has generally been followed, even though it sometimes looks a little disconcerting. A possessive term bereft of an apostrophe, for example, jars at first sight. However, this rule avoids any uncertainty over the recording of wagon examiner's hut or wagon examiners' hut. It will always be indexed as wagon examiners hut regardless of the number of examiners that use it.
Terms are either 'preferred' or 'non-preferred'. Only preferred terms appear in the hierarchies and it is these terms that should normally be used for indexing. A non-preferred term is a term that has the equivalent meaning to the preferred term but is not used for indexing. This might be because the term is:
It should be noted that synonyms are still being identified amongst the terms listed in this thesaurus and further refinement can be expected in future editions. Suggestions for the elimination of synonyms that currently share preferred term status would be much appreciated (see section 1.7 below).
Preferred terms are placed into hierarchies. Terms are gathered into groups sharing similar concepts. Then terms in each conceptual group are ordered into levels going from the broadest, most general type of term to the narrowest and most specific type of term.
For example:
vehicle
locomotive
steam locomotive
wood burning locomotive
In any such hierarchy, the 'parent' term lying immediately above a particular term is said to be a Broader term of that term whilst a 'child' term directly below it in the hierarchy is a Narrower term. Thus in the above example, vehicle is a broader term of locomotive whilst steam locomotive is a narrower term of locomotive.
It is a fundamental rule of thesaurus construction that, with a few exceptions, all child terms should be a kind of their parent. Thus all steam locomotives are a kind of locomotive and all locomotives are a kind of vehicle. Applied in the other direction, only some vehicles are locomotives and only some locomotives are steam locomotives.
This all/some rule helps avoid inappropriate hierarchical arrangements such as:
vehicle
locomotive
steam locomotive
firebox
Whilst a firebox obviously has something in common with a steam locomotive, it does not belong here as a firebox is not a kind of steam locomotive. It is necessary to construct a parallel hierarchy for components:
vehicle component
locomotive component
steam locomotive component
firebox
Now the rule is satisfied as some steam locomotive components are fireboxes and all fireboxes are steam locomotive components.
It should be noted that some railway terminology appears to defy the expected parent/child logic. For example, anybody unfamiliar with railway practice might expect a banana van to be a species of fruit van. However, due to the way that the railway industry has traditionally described these vehicles, they are siblings. A fruit van is a particular type of vehicle for the conveyance of produce requiring a well ventilated environment and is not at all suitable for carrying bananas, which require an insulated and heated vehicle to complete the ripening process whilst in transit.
A thesaurus can be poly-hierarchical. That is to say, a broader term can appear in more than one hierarchy and under more than one class (for example, a guard's flag could appear in two hierarchies under two separate classes).
| Control and communications class hand signalling quipment flag guards flag signalmans flag |
Tools and equipment class guards equipment guards bag guards flag guards watch |
In this example, guards flag has two broader terms: flag and guards equipment.
In practice, poly-hierarchical relationships have been kept to a minimum in this initial version due to technical difficulties in managing the data.
In the creation of hierarchies a situation can arise where a term has a large number of narrower terms and these clearly fall into several easily identifiable groups but there is no recognised index term for these groupings. Consequently, either a descriptive phrase (e.g. 'foodstuff carrying vehicles') or an artificially contrived term (e.g. 'wheelbearers' for rails and plates) must be employed in order to bring together terms with a common concept. The grouping term itself is not to be used for indexing purposes (and is hence known as a non-index term). In this thesaurus grouping terms can be easily distinguished as they are unemphasised and enclosed within angle brackets (for example, <foodstuff carrying vehicles>) whilst an index term is identified by bold type (for example, banana van).
It is sometimes necessary to specify on what basis the terms have been grouped within a hierarchy. In these instances a term may be subdivided using facet indicators that show which of its characteristics form the basis for subsequent grouping. Facet indicators are non-index terms. They are distinguished by the same typography as grouping terms (i.e. unemphasised and enclosed within angle brackets).
For example, narrower terms of locomotives can be grouped according to various characteristics:
vehicle
locomotive
<locomotives by power source>
diesel locomotive
steam locomotive
etc.
<locomotives by function>
passenger locomotive
shunting locomotive
etc.
<locomotives by wheel arrangement, etc.>
articulated locomotive
tank locomotive
etc.
<locomotives by adhesion method>
rack locomotive
Preferred terms can be associated with other preferred terms that have similar concepts, but are not synonymous and do not satisfy the all/some test. These types of terms are known as related terms and show an associative relationship. They obviously have something in common but do not have a parent/child relationship and will usually be in different hierarchies. Related terms help enquirers extend their search laterally to find terms that, although not describing the same kind of object, share a common subject and may therefore be of interest.
For example
rack rail RT rack railway
The term rack rail is a narrower term of <rails by function> in the Track and track components Class whilst rack railway is a narrower term of <self-propelled railways by adhesion method> in the Railway types Class. They are in different hierarchies but each might be of interest to a researcher who requested the other term.
As has already been stated, the terms in this thesaurus are grouped by classes and not by the broadest noun term (Top Term). These groupings are intended to aid searching and retrieval but are not part of the hierarchy of terms.
Railway objects are included in a particular class on the basis of the criteria set out in the class definitions (see Section 1.6). Class names are included in the alphabetical listing, where they are distinguished by being printed in unemphasised capitals.
A scope note provides a definition of the object to which the term applies and is to be used only in the context of the thesaurus, as some terms that are used rather loosely in every day parlance are given a more strict definition here. The scope note may occasionally include guidance for the use of the term.
Literary warrant provides an example of the usage of the term in a published source. Time has not allowed an exhaustive literature search, so where we have been unable to trace a term in a published work, an acknowledged expert in the relevant field has been quoted as the authority for its inclusion.
It should be noted that references given as literary warrant are not necessarily the source for the exact definition given in the Scope note. In many cases, scope notes are based on information gleaned from a number of sources.
As stated previously, the singular form of preferred terms is used in accordance with normal custom and practice in the heritage sector. However, to facilitate integration with other sectors, where the plural form is irregular (i.e. it cannot automatically be derived by appending an 's' to the singular), the plural form is also provided in the Alphabetical list. Grouping terms and facet indicators are always given as plurals as they relate to groups of narrower terms and are not intended for indexing.
Some objects represent multiple concepts and are named by the cumulative addition of descriptors. For example, an inside cylinder compound locomotive or a childs privilege return ticket. Such names are referred to as 'compound terms'. An inside cylinder compound locomotive is both an inside cylinder locomotive and a compound locomotive. Each of these concepts can be indexed separately. This will improve retrieval, as a search for compound locomotives will find inside cylinder compound locomotives without recourse to hierarchical linkages. Perhaps more importantly, it obviates the need to congest the thesaurus with endless permutations of terms. The process of breaking down compound terms into a number of simple concepts is known as factoring.
Whilst a few representative examples of compound terms have been included in this thesaurus as non-preferred terms, most have been omitted. It will, of course, still be necessary to record the full term in the catalogue record in addition to the simple indexing terms.
This thesaurus is laid out in two sections: the Class List and the Alphabetical List (see Figure 1). The Class List shows the hierarchical layout of the thesaurus within each class. It only includes the preferred terms. The Alphabetical List includes both preferred and non-preferred terms. In each case, natural language order is used and there is generally no punctuation (see Glossary). The same conventions are used in both the class and alphabetical displays. All terms are in lower case except where the term is derived from a proper noun, when an initial capital is used. Indexing terms are shown in bold and non-preferred synonyms in italics. Other non-indexing terms (for example, grouping terms) are displayed in normal type and enclosed by angle brackets.
The Class List shows the broader and narrower preferred terms in a hierarchical structure. Indentations within the class list reflect the Broader and Narrower relationships, with narrower terms being indented more than their parent terms. Grouping terms and Facet indicators are also shown in the Class List as they may be broader or narrower terms of preferred terms. The class term always appears at the top of each Class List page.
The Alphabetical List provides information on status (is the term preferred or non-preferred) and relationships (is it a narrower or related term). The full hierarchy of a term is not included in the alphabetical list; it shows the class of the term and one hierarchical level above and below. If a term belongs to more than one class, or if there is more than one broader term then the term is repeated in the alphabetical list.
Figure 1 The layout of the Class List and Alphabetical
List
Strictly speaking, non-preferred terms should not be included amongst Narrower Terms in the alphabetical listing but due to a software problem, some do appear in this edition.
The online thesaurus contains both alphabetical and class listings with hyperlinks between them, making navigation much easier than in the printed version. Arrows alongside terms in the Class Lists represent hyperlinks to the corresponding term in the Alphabetical List. Similarly, arrows alongside terms in the Alphabetical List represent hyperlinks to the corresponding term in the appropriate Class List.
A printed version of the thesaurus can be purchased from mda. It contains both alphabetical and class listings but obviously lacks hyperlinks.
The on-line version may be made available on CD-ROM if there is enough demand for this and raw data may be made available for licensing to system developers. All enquiries should be addressed to mda.
The Railway Object Thesaurus includes the following Classes:
Comprises complete railway systems. Specific types of track, etc. are allocated to the Track and track components class.
Comprises built complexes (yards, stations, etc.), individual buildings and fixed structures and their components. Fixtures and fittings are included but tools and portable equipment, furniture, etc. will normally be covered by the Tools and equipment class. Signal structures (e.g. gantries) are covered by the Control and communications class.
Comprises records and equipment associated with the commercial operation of a railway company or network including ticketing, freight invoicing and routing, advertising, etc. Includes general administration, finance and personnel management but does not include rules and regulations (e.g. rule books) or equipment and documents concerned with the safe and efficient working of trains (e.g. weekly traffic notices), these are covered by the Control and communications class. Commercial buildings are included in the Built works class.
Comprises structures and equipment associated with the control of trains. Includes operating rules and regulations, timetabling, train rostering, train control, signalling and telecommunications. Signalling covers the operation of points and signals, block signalling, automatic train control, road level crossings, etc. This class does not include public timetables (these are covered by the Commercial records and equipment class). Control buildings are included in the Built works class. Some communications equipment used by staff other than signalling operators is allocated to the Tools and equipment class (e.g. guards' whistles and flags, lookout's horns and flags).
Comprises tools and portable equipment, furniture, etc. Fixtures and fittings will normally be included in the Built works class. Some portable signalling equipment and tools (e.g. signalman's lamps and flags, reminder appliances, point clips, detonators, etc.) are allocated to the Control and communications class.
Comprises track types, assemblies, sub assemblies and individual components. Includes the trackbed, rail supports, rails and associated features such as rail lubricators, etc. Also includes individual lines of track (e.g. fast line, goods line, up line, passing loop, siding) but not a complete section of railway (as in branch line, junction, etc.) which is treated as a route complex in the Built works class.
Comprises locomotives, rolling stock and their component parts. Some tools and equipment carried on rolling stock are allocated to other classes. Headcode discs, headlamps, tail lamps, etc. are included in the Control and communications class, even when they are built into the vehicle (e.g. permanently wired electric head and tail lamps).
The thesaurus is a dynamic indexing tool and will evolve with further use. It should be stressed therefore that this published version is only a 'snapshot' of the thesaurus at the time of publication and is subject to ongoing addition and amendment.
The Railway Terminology Working Group will continue to meet at regular intervals to consider new terms or amendments to the thesaurus as they arise. Suggestions for additions or amendments can be sent to the Group using the Comment or Candidate Term forms included in this publication and every attempt will be made to respond to any suggestions within a reasonable period of time. Anyone wishing to receive further information on the thesaurus or data standards should contact:
| MDA 22 Hills Road Cambridge CB2 1JP |
Telephone: Fax: Email: |
01223 316028 01223 364658 mda@mda.org.uk |
The text of this version has slightly been change from that of the paper-based version. For example the Candidate Term Form and Comments Form, in this version, allow for on-line submission. Also the MDA contact details have been updated
| © Collections Trust 2008. You may freely download this page for non-profit use, but must acknowledge Collections Trust (formerly MDA) & the Railway Terminology Working Group in any output in which it is used. |