Hmm …

… Secrets of the Stacks — Book Excerpts — Medium.

CREW stands for Continuous Review Evaluation and Weeding, and the manual uses “crew” as a transitive verb, so one can talk about a library’s “crewing” its collection. It means weeding but doesn’t sound so harsh. At the heart of the CREW method is a formula consisting of three factors—the number of years since the last copyright, the number of years since the book was last checked out, and a collection of six negative factors given the acronym MUSTIE, to help decide if a book has outlived its usefulness. M. Is it Misleading or inaccurate? Is its information, as so quickly happens with medical and legal texts or travel books, for example, outdated? U. Is it Ugly? Worn beyond repair? S. Has it been Superseded by a new edition or a better account of the subject? T. Is it Trivial, of no discernible literary or scientific merit? I. Is it Irrelevant to the needs and interests of the community the library serves? E. Can it be found Elsewhere, through interlibrary loan or on the Web?

Better to spend time thinking than to spend it composing acronyms.