remainder mark : Usually an ink marking of some sort which indicates that the book was designated a remainder. In most cases, it can be found on the edges of the text block in the form of a marker stripe or a stamp of some sort.

Remainder marks considerably lower the overall collectibility of a title, although, in some cases, they are acceptable to a collector.

4to : Or quarto. A term used generally to describe the approximate size of a book, a book that is about 10" to 12" tall and roughly squarish in shape. The term is based on the size of paper traditionally used by book printers which has been folded and cut into 16 pages.