It is not always necessary or appropriate to assign genre and physical characteristic terms. An institution may decide to index only selected material to exemplify a particular genre or physical type in its collections. P&P usually assigns a physical characteristic term to assist retrieval by media categories. It is based on the physical description vocabulary in MARC field 300. Pictures with clear topical subjects do not invariably need a genre term (in fact, CITYSCAPES, GENRE WORKS, LANDSCAPES, PORTRAITS, and STILL LIFES are genre terms that are intended chiefly for assignment in the absence of other subject matter. They are not meant for every image of a city, domestic scene, mountain, or person.)

More than one term may be needed to express the various categories an item or group represents. The 655 field is repeatable for this reason. Although without specified limits, selectivity in the number of terms assigned is recommended.

Example: An allegorical crayon drawing made in memory of a dead hero and intended to illustrate a magazine article, but then never published, could be indexed with: ALLEGORICAL DRAWINGS, MEMORIAL WORKS, PERIODICAL ILLUSTRATIONS, PROPOSED WORKS, and CRAYON DRAWINGS