A Library Numbering System

The following is a description of the Pratt Filing System, used to file books, periodicals, copies, quotations, and references. The system has the following features.

• Items are grouped first by location. In addition to the major areas such as shelves and file cabinet, they are also divided into several heights to better use limited shelf space in a small library.

• Items in a given area are grouped by subject and then subgrouped by author surname.

• Subjects are ordered in a personalized logical sequence to distribute entries evenly and to facilitate finding items of related subjects.

• Items may also be listed under many subjects in a topic index.

• Each item is given a number which uniquely determines its location, subject, author surname and size. References in the topic index refer only to this number which allows the item to be found.

The ID code given to each item is of the form LNNAI, where L determines the general location, NN is a two digit subject number, A is the author's surname initial, and I is the item number. Each of these will now be described.

Location. The first letter of the item ID code is a one letter code indicating location. Codes A-F refer to the bookshelves, code J to the journal area, and codes S and X refer to the file cabinet. Code R references articles contained in other books or periodicals.

Book shelves are divided into 6 heights (A-F):

A. Paperback size:	Height < 7.25"
B. Softbound size:	Height < 8.5"
C. Textbook size:	Height < 10.3"
D. Full size:	Height < 11.7"
E. Oversize:	Height < 12.8"
F. Flat books:	Height > 12.8" or Width > 12".

If it is desired to locate periodicals separately from the books, they are given the location code J (for journals). Only one ID code is given for the entire journal.

Separate articles contained within larger volumes in the library can be given individual ID codes. The location code R references such entries, usually to be found in periodicals or books which are a collection of articles. The actual location is found under REF discussed below.

Items in the file cabinet are divided into two categories. Location code S is for a single article per folder, and X for many Xerox copies per folder. S and Xcopies are filed in different drawers or cabinets.

Subject Number. The subject numbers range from 00 to 99 and should be chosen to meet the needs of the particular library in question, using the following criteria.

1. There should be at most 100 categories in all (numbered 00 to 99). Keeping the number to a two digit integer facilitates computer filing. The drawback to this feature is that it is difficult to add new subjects after the system is set up, but it is anticipated that this system will only be used for a private library that is already well established and the subjects will be known.

2. The subjects should be logically contiguous, that is, similar subjects should be near each other so that a book that is difficult to categorize will be easier to find without the ID code.

3. All possible subjects should be included, to allow for new books on new subjects. However, for this system to be effective, it is best that only a few such books on unplanned subjects be added.

4. About 1% of the books should be in each subject to get maximum spread of through the 100 categories.

5. A convenient but non-essential feature would be to have each of the subject numbers divisible by 10 be a major heading. This facilitates remembering the numbers.

It is very difficult to meet all of these requirements. To meet both requirement 3 and 4 demands a balance between generality, to meet future needs, and specialization, to evenly distribute the items in the existing library.

The subjects chosen for the John Pratt library are listed in the following table. They were chosen for his special needs after he had already aquired well over a thousand books. He has allowed ten categories for astronomy (30-39) and another ten for ancient astronomy (40-49). His grouping would not meet criterion 2 for a historian because history is spread over categories 9, 21, 39, and 50. However, for Pratt's work these are contiguous classifications.

Author Initial. The next element of the item ID code is the first initial of the surname of the first author of the work. This may also be that of the translator or the editor if it seems more appropriate. If there is no name to use, the publisher or the title of the work is used.

Item Number. The f if th and final digit of the item ID code is the item number. It may be assigned in any order: of acquisition of the item, of publication date, or of the random order of initial cataloging.

The item numbers begin with 0 and go through 9, continue with A through Z, and then from a through z, so 62 items of the same location, subject and author may be cataloged.

The exact location of an item is usually determined by the ID code. The location code identifies the area, and items are then filed in order by subject number, by author initial and then by item number. Thus item B3OA3 would be found immediately after item B3OA2 in the B size shelves. The next item might be B3OA3 if there is another book that size on subject 30 by an author with surname initial A, or perhaps B30FO if the next book that size on that subject has author initial F (and none with author initials B-E), or perhaps B32WO if there are no more books that size on subject 30 or 31, and no books on subject 32 with author initials A-V.

The exception to the rule that determines exact location is for location code R because these refer to articles located within items with separate ID codes (which will have location codes J or A-F respectively). Such items will note the ID code of the source in the bibliography data described below.

There is another one-character "type" code which is not part of the ID code, but which provides further information for possible use in data base programs.

Binding Types. For items with location codes A-J (books and periodicals) , it describes the type of binding as follows:

B	Three-ring Binder
C	Comb bound
E	Vellum edge bound
F	Folded and Stapled
H	Hard bound
M	monthly Periodical
N	Named volumes of a set
P	Paperback
Q	Quarterly Periodical
S	Soft bound
T	Stapled and Taped
V	Volumes of a set, unnamed
W	Spiral wire bound

Source Types. For items in the f ile cabinet, no binding type is necessary. In these cases, the type code is used to identify the source of the item as follows:

a	Letter, REF is addressee
i	ID code in Pratt Library
p	REF is a City: Publisher
q	Quotation, REF is source
r	REF is a Periodical Ref.
s	REFerence is the source
u	Unpublished

A topic index can be created to list a single item under multiple topics. only two fields are required per record: the topic and the location. The location is the ID code followed by the page number if needed. In the case of items with location code R, meaning that they are really small articles found within a larger referenced source, the original source ID is given.