Filler. A collectors term for a specimen in low condition intended to be replaced by a better specimen at a later time. Since items in collectible condition should be easy to obtain, fillers are usually of varieties of extreme rarity. Thus it is better to have some example of a rare variety than none at all.
excerpted with permission from
For Artists, Makers, Collectors and Curators
COMPILED AND WRITTEN BY D. WAYNE JOHNSON
Roger W. Burdette, Editor