The call number order, the correct order for shelving, is greatly complicated
by the use of letters in the first line, the distinction between capital and
small letters, and the use of line division as an element.  The logic in the
system is not immediately apparent.  More care in the original establishment
of the system might have made things easier for patrons and staff.  Many
books are "lost" by misshelving and it pays to search for a book in one or
more "wrong" places based on simple errors.

The rules can be consolidated into two points, although examples will help to
clarify them.

1.  The division into lines is significant.  Identical first lines file

2.  Compare within lines character-by-character.  The sequence is: nothing, A
to Z, 0 to 9, a to z; the decimal point is ignored.

The following are real call numbers in correct order.  Numerous intervening
call numbers are omitted to make the examples shorter.  Refer to the
shelflist for more.

Sequence of common types of call numbers, illustrating most of the rules:

978	978	978Ad4	978Ad4	978Y82
Am35	Z2	Ad4	W585	C91

978.08	978.1	978.1	978.1	978.1Ab37
B52	AW418	Ar77	Y351	B976

978 is New York; 978.1 is North Carolina.  Cutter numbers on the first line
indicate cities or counties. Second lines shown here are all Cutter numbers,
except 978.1 over AW418, which is A for Bibliography, from the alphabetic
form table, followed by a Cutter number.  Note that 978 (978nothing) comes
before 978Ad4, as "nothing comes before something"; 978Y82 comes before
978.08 (A-Z before 0-9); and AW418 comes before Ar77 (A-Z before a-z).

Sequence showing the voluminous author "double capitals":

823SA	823SA	823SA1	823SP3	823SZ	823Sa17	823Sp3
B28	St82 	F71	I22	W24     I	I24

823SA-SZ capitals is the "voluminous author" Shakespeare; the Cutter numbers
823Sa-Sz with small letters are used for other authors of the period whose
names begin with S.  Since S is a letter that takes a small letter after it
in the Cutter author table, confusion results if the distinction between
capital and small letters is ignored, particularly with 823Sp3 Spenser which
shelves quite a bit down the aisle after 823SP3 Shakespeare.  Books in this
section are continually misshelved.

Sequence showing 2-digit numbers:

87CA	87CB	87CR5	87C16	87C16	87OB
D45	Ab3	KM	BA	ZZ	C47

87OX	87Ob7	87PB	87V34	870	870
KI	ID20	C69	IF46	AF1	AOg4

Here is a section full of voluminous authors and special tables; the
distinction of 87OB and 87Ob is similar to previous sequence.  Note also here
the seeming ambiguity of 87O (letter O) and 870 (zero), which can be resolved
by recalling that 870 (zero) is never followed by letters on the first line.

Sequence showing relative order of number and small letter:

825Y27	825Y892	825Ye3	825Ye3	825Yo8
Q5	W	A5	Y61	BM

The choice of 0-9 versus a-z comes up only in a few places involving special
tables. Here the Ye3 and Yo8 pseudo-Cutter numbers are unique.  Another area
with this choice is 838-839.

Sequence showing variant second lines:

The first line is:  328.734 .  The second lines are as follows:

A   AJ61   AW971   A1   A4   B693   Un34   01   038   1   13095

This is a very odd case that really tests one's knowledge of order.  The call
number is for US Government Documents.  Second lines beginning A are
bibliographies, but note mixture of A alone, A with Cutter number, A with
number.  Numerous books about government documents are in B693 to Un34 using
Cutter numbers.  Following that is the "serial set" in numerical order
(although the zero 0 looks like, and may sometimes be found shelved as,
letter O).  There is only one departure from normal order: the set starting 0
is intended to be in order of whole numbers after the zero, like 09 before
010; and the main set of 1 to 13095 similarly is arranged in whole number
order rather than character-by-character (decimal order).

Small L:

The small letter L, l, tends to look like number 1 when used in Cutter
numbers, as Al2.  On some books a simple stroke | is used, and on cards the
ambiguous typewriter character l is used.  Because of the ambiguity, however,
small L is often written as script l, or as a capital L.  The capital L
solves one problem but creates another, since it would file differently if it
were "really" a capital: some call numbers must therefore be read as "capital
L meaning small L" (!) if one is to shelve them correctly, as for example
812EL46 for T.S. Eliot (and at this writing one Columbia library has its
D812EL46 all filed before D812Eb36, which is correct and yet not correct).