QM - describes the broad subject or Main Class and subclass. Within class Q for Science, for example, QM represents the subclass Human Anatomy
23.2 is the classification number, which defines the subject matter more finely
.M348 - is the cutter number and usually describes the author's last name or title of work though it may also represent further subject subdivision or geographic area. Sometimes there are double Cutters. Read in alphabetical order, then the number as a decimal.
2001 - date of publication: read in chronological order
