TGM II is designed to provide terms for access to categories of media and formats rather than to enumerate terms for indexing every conceivable aspect of graphic materials. It is not an exhaustive glossary. The degree of term specificity is meant to permit reasonably direct searches to locate the most commonly requested examples of graphic materials. Some terms for relatively rare material have been included, when such materials are commonly requested and hard to locate.
The need for access to categories of material outweighed the desire for access to very specific types that require great technical expertise, considerable analysis, or elaborate tests in order for the cataloger to assign a term. The identification of some processes may, in fact, depend entirely on the presence of manufacturers' labels, captions, imprints, or accompanying information. However, retrieval of some formats and physical types that are difficult to recognize cannot be neglected. For example, while it may be excessive to analyze every photographic print for indexing by a specific photographic process, terms have been included for processes that are fairly readily identified and that could help meet the demand for study examples.
The variety of material found in graphic collections prompted some modification of ambiguous informal terminology. For example, in a purely photographic collection, the words "prints" and "negatives" may suffice. In a mixed collection or in a database of records for a variety of material, however, "prints" is better reserved for engravings and related media, while "photographic prints" refers without confusion to photographs. Such formal vocabulary is necessary for indexing purposes, even though the notes in the catalog record continue to be expressed in informal language.
Based on experience gained since the first edition, terms have been added to specify graphic material content and distinguish it from textual genres. This has been done because so much pictorial material is found in catalogs for mixed or textual collections.
Examples: PICTORIAL ENVELOPES (instead of just Envelopes) PRINTMAKING EQUIPMENT (instead of just Equipment)
Graphic designs and their finished products (e.g., BOOK JACKETS) are in the category of materials in which pictorial content is implicit in the term, so the word "Pictorial" is not part of the phrase; the design work may also be indexed with GRAPHIC DESIGN DRAWINGS. Different manifestations of an object type are also brought together under the same term; all possible physical forms of a genre are not given special terms. Thus, PLAYING CARDS includes both the cut and uncut sheets. With ARCHITECTURAL DRAWINGS, which may be hand-drawn, photographic, or printed, separate headings such as BLUEPRINTS are used to convey the physical characteristics.
As in the first edition of this thesaurus, certain types of vocabulary have been excluded. Terms that describe art movements or styles as well as those requiring subjective judgment, such as documentary photographs, pictorialism, propaganda, and primitive paintings, are beyond the scope of TGM II.
Terms that combine broad subject categories and forms have, however, begun to be included, thus providing more direct access to well-established categories of material that catalog users are likely to request, e.g., BASEBALL CARDS and BOTANICAL ILLUSTRATIONS. The fullest example is under POSTERS. (For example, instead of searching a database for the topical term DANCE and the form term POSTERS, now one can search for DANCE POSTERS.) The phrases reflect typical categories for filing posters, listing them in auction catalogs, or writing about them in books. The phrases also draw together posters which may have many different subject headings that cannot be easily retrieved together, e.g., WAR POSTERS indexed under the names of many different wars; POLITICAL POSTERS indexed under presidential elections, protest movements, and other subjects.
The new edition also includes a few historic trade name processes that are more recognizable than more generic expressions of the material. Examples include AUTOCHROMES (instead of Screen color glass transparencies) and PHOTOCHROM PRINTS (instead of Photomechanical prints--Color). To provide access to the numerous trade names not included here, the names may be stated elsewhere in the catalog record. Other terms often used in the descriptive portion of the catalog record have also been excluded because they do not seem practical as access points. Among these are: contact prints, copper engravings, die-cut lithographs, glossy prints, and half-length portraits.
The complex formulation of a string of words to express a description such as "pen, pencil, ink, and graphite drawing with blue wash on laid paper" cannot be accomplished within the structure of TGM II with its emphasis on basic categories and simple subdivisions. Separate terms were, therefore, established to designate application instruments (e.g., PENCIL WORKS). Terms that describe the primary and secondary support material were largely excluded in favor of medium designations. Since, however, the primary support may sometimes be the only distinctive feature of a photograph, terms for support were coupled with general photographic terms (e.g., CERAMIC PHOTOGRAPHS, FILM NEGATIVES). For institutions employing the MARC format, codes in the 007 field provide access to primary and secondary support materials, such as paper, glass, and wood. Information about the support material and application instrument may also appear in the physical description or note area of the catalog record.
Several genre terms (e.g., ABSTRACT WORKS, ALLEGORIES, CITYSCAPES, GENRE WORKS, LANDSCAPES, PORTRAITS, STILL LIFES) were combined with general physical characteristic terms (DRAWINGS, PAINTINGS, PHOTOGRAPHS, PRINTS) in order to provide a means for dividing up large files of catalog records indexed by a general term. For example, an extensive file of portraits may be broken into categories for PORTRAIT DRAWINGS, PORTRAIT PAINTINGS, PORTRAIT PHOTOGRAPHS, and PORTRAIT PRINTS.
TGM II is not a theoretical list; rather, it is a practical representation of categories of material encountered at the Library of Congress and other extensive American historical collections. Standard reference sources and cataloging manuals (cited in the bibliography) were reviewed to find common vocabulary and determine relationship hierarchies. Some terms and their definitions were drawn from colleagues' personal knowledge. Other thesauri, especially the Art and Architecture Thesaurus (AAT) and the Library of Congress Subject Headings (LCSH), are always consulted for terms to incorporate into this graphic materials thesaurus. TGM II terms match AAT or LCSH vocabulary in order to simplify retrieval in union catalogs. A paper authority file record documents the sources or literary warrant for each TGM II term.
None of the consulted sources could serve as a single thesaurus for historical graphic materials. Because they are either too narrowly focused and detailed for highly diverse collections of graphic materials, too general in the terminology related to graphic materials, or incomplete in areas such as pictorial ephemera, the existing lists do not have an appropriate relationship structure for the desired universe of terms. In addition, most lack definitions or guidelines for application that would help catalogers and researchers in graphic collections use the thesaurus. It is expected that terms for genre and physical types occurring less frequently in pictorial collections (e.g., ALMANACS or DIARIES) can be taken from the authorized thesaurus most appropriate for the particular type of non-pictorial material.