Books (including ebooks), journals, kits, videos and DVDs in the USC Library are shelved in order of Library of Congress call number. Call numbers on books and journals appear most often on the spine or on the front cover if the spine is too narrow.
The Library of Congress classification system uses alphabetical, numerical, and decimal order.
Here's a sample call number, with explanation of how this affects the way the item is shelved:
HN - letter line, describes general subject area; shelved in alphabetical order
49 - number line, narrows subject area; numerical order (whole number, not decimal).
.P6 - cutter line, further narrows subject area OR specifies author; alphabetical then decimal order
H56 - 2nd cutter line (if present) also in alphabetical then decimal order
1995 - year of publication, numerical order
Every title in the collection has a UNIQUE call number, but extra copies of a book or DVD will have an identical call number.
Different editions of the same book will have the same basic call number EXCEPT for the date at the end.
Here's a full list of all LC call numbers.