Thesaurus for Graphic Materials I: Subject Terms (TGM I)
INTRODUCTION (1995 printed edition)

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I. TGM I: Summary of Features
I.C. Structure and Syntax

I.C.1. Relationships

TGM I is a thesaurus in alphabetical format. As stated previously, TGM I conforms to the ANSI standard for structure and syntax. "Postable" terms (terms that are authorized for indexing) and "non-postable" terms (cross references pointing from unauthorized to authorized terms) are interfiled. Under each authorized term, the reference structure includes unauthorized terms (UF), broader terms (BT), narrower terms (NT), and related terms (RT). For each relationship that is established in the thesaurus, its reciprocal relationship can be found at another point in the thesaurus.

Example: Building dedications          (authorized term)
          UF  Dedication of buildings  (term not authorized)
          BT  Dedications              (broader authorized term)
          NT  Church dedications       (narrower authorized terms)
              Cornerstone laying
          RT  Buildings                (related authorized terms)
              Groundbreaking ceremonies
              Toppings out

         Dedication of buildings
          USE  Building dedications    (cross reference from unauthorized
                                       term to authorized term)

Used for (UF): A term that is not authorized for indexing. UF terms are listed primarily for editorial purposes, but they may help searchers by clarifying the scope or meaning of a term. The reciprocal is USE.

Use (USE): A cross reference that points catalogers and searchers to an authorized term. USE references may be made from synonyms, near synonyms, antonyms, inverted phrases, or other closely related terms or phrases. The reciprocal is UF.

Broader term (BT): An authorized term which indicates the more general class to which a term belongs. Everything that is true of a term is also true of its broader term(s).

Narrower term (NT): An authorized term which is narrower in scope and a member of the general class represented by the broader term under which it is listed. The reciprocal is BT.

Related term (RT): An authorized term which is closely related to the term under which it is listed, but the relationship is not a hierarchical one. The reciprocal is also RT.

Although no precise rules dictate when related term references should be supplied, some typical situations include:

TGM I tends to be generous in supplying related term references. This is partly because relationships that would be implicit in a hierarchical display of the terms are less apparent when the terms appear in an alphabetical display. In accordance with thesaurus construction guidelines, however, related term references are never made to two terms at different levels in the same hierarchy.


       Game industry  NOT  Game industry
        RT  Games           RT  Games
                                Board games   
                                [a narrower term to Games]

More detailed definitions and discussion of hierarchical and related term relationships can be found in the ANSI standard.

I.C.2. Syntax

In accordance with the ANSI standard, terms are selected based on common usage and are established using natural language word order and modern American spelling conventions.

I.C.2.a. Single terms

Headings for concrete concepts are established in the plural:

Example:  Theaters

Headings for abstract concepts are established in the singular:

Example:  Civilization

Headings for activities are established as gerunds:

Example:  Banking

I.C.2.b. Compound terms

Compound terms are established (1) when a single concept is expressed by multiple words in natural language, (2) when it would be difficult or unnecessary for an indexer to differentiate between two closely related concepts, and (3) when splitting them into single terms to be placed in separate fields would lead to retrieval of irrelevant material.

Example:  Artificial flowers
          Cattle ranches
          Educational organizations
          Real estate development
          Tobacco industry

Compound terms are always expressed in natural language order, never inverted:

Example:  Protestant churches  NOT   Churches, Protestant

Compound terms which include the word "and" are used when two terms occur together with such frequency that it would be undesirable to establish them separately. Such terms are constructed with an ampersand (&) in order to differentiate in retrieval systems between the use of "and" as a Boolean operator and the use of "&" as part of an indexing term:

Example:  Doors & doorways
          Good & evil

I.C.2.c. Parenthetical qualifiers

Qualifiers are used to differentiate between homographs.

Example:  Camouflage (Biology)
          Camouflage (Military science)

I.C.3. Facet indicators

Facet indicators, which appear in brackets directly underneath authorized terms, signal that a term may be subdivided by geographic and/or nationality designations.

Example:  Military camps
          --[nationality]--[country or state]--[city]

These indicators have been included on a systematic basis with certain categories of headings; with other types of headings, they are added as need arises in P&P's cataloging. (See Section III for further information about using geographic, nationality, and other types of subdivisions.)

I.C.4. Notes

TGM I uses several kinds of notes to help catalogers apply terms consistently and to help researchers find appropriate search terms.

I.C.4.a. Public note (called "Scope note" as of 2007)

The public note (PN) defines a term, explains its scope, or helps a user understand the structure of the thesaurus.

Example:   Bison
           PN     For the American buffalo. Search under BUFFALOES 
for buffaloes of the eastern hemisphere.

I.C.4.b. Cataloger's note

The cataloger's note (CN) clarifies how to use a term or when to use it in conjunction with another term ("double indexing").

Example:  Sick bays
          CN     Double index under type of vessel.

The note "TGM II term," which occurs frequently throughout TGM I, refers to terms which also appear in Thesaurus for Graphic Materials II: Genre and Physical Characteristic Terms. (See Section II.E. for guidance on application of these terms.)

Example:  Stereographs
          CN     TGM II term.

Notes beginning with the phrase "Used in a note under ..." are of value primarily in editing and maintaining the thesaurus.

Example:  Doves
          CN     Used in a note under SYMBOLS.

I.C.4.c. History note

The history note (HN) records the fact that a change has taken place in a term or the status of a term since the publication of the first edition of TGM I. This may prove useful to searchers since it suggests terms that may have been in use formerly and that should be checked to retrieve older catalog records. Generally, if one term has been completely replaced by another term, the older term appears as a "UF."

Example:  Draft 
          HN     Changed 11/1987 from COMPULSORY MILITARY SERVICE.

I.C.5. Filing conventions

The thesaurus maintenance software (LEXICO) used to produce TGM I follows ASCII filing rules. Thus,

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