Tom Hutchinson's question about the best way to categorize and
shelve music rolls is one that a librarian might try to answer.

The Library of Congress (LC) developed over many decades of the last
century an elaborate and detailed classification system that provides
a number and a place for every particle of every aspect of human
endeavor.  The final piece of the puzzle, class K for law material,
was completed only in the 1990's.  Books are arranged on shelves
according to the LC classification system and the classification
schedules, which are massively elaborate, are published in 41 volumes
for the use of other libraries.

Much money, time, and intellectual effort is spent assigning a book
to its correct place on 500+ miles of book shelving at LC, but the
result is that you can -- or used to be able to; see my final paragraph
below -- go to a shelf and find not only a specific book but others
like it.  Browsing the shelves was a good way of picking up additional
sources of information.

The downside of this system, in addition to the difficulty of
analysis and subject assignment, is that it means a constant shifting
of items on a shelf to make room for new items that need to go there.
A lesser downside is that many books are on more than one subject and
therefore should ideally be shelved in more than one place, which is
physically impossible.

Present-day classification thinking is to do the grouping and
classification only in your online system.  The physical items
represented by the entries in your system are simply put on the shelf
in numerical order in the order they are received.  The power of the
online system can be used to group, sort, retrieve records for items,
using data entered into the system.  Once you find the records for the
items you want, you can use the simple sequential shelf number of an
item to go to the shelf and pull it off.

It's Tom's call as to which way he wants to go.  But today LC rather
regrets its traditional shelving system.   Around 1990 LC was forced
to abandon its "open stacks" policy, where employees and many users
were given access to the shelves, in order to stem the growing amount
of willful damage to books, particularly those in class N (Art).
LC book stacks are now closed and shelf browsing is not possible,
eliminating the need for shelving by subject.

Matthew Caulfield
Irondequoit, New York