To verify completeness of a book by examining it carefully. For books produced in the hand-press era, this involves some knowledge of format. The leaves in a gathering must be counted and deviations from the expected count noted. Then the book should be compared against a known complete copy, or with a comprehensive bibliography. At this point, the book seller’s description should note how, if at all, the copy at hand is different from a complete copy. The expression of the complete sequence of a book is known as a Collation.