College and Research Libraries


By J O H N A L B E R T S A N F O R D and F R E D E R I C K R. T H E R I A U L T 

Problems in the Application of Uniterm 
Coordinate Indexing 

Dr. Sanford is deputy chief, Technical 
Library Division, National Security 
Agency, and Dr. Theriault is chief of the 
documentation branch. 

T' H E L I B R A R Y of the National Security Agency has completed the organiza-
tional and experimental work necessary 
for the creation of a large-scale Uniterm 
coordinate index. Production is now on 
a r o u t i n e basis. Over 70,000 documents 
have been cataloged. T h i s report is writ-
ten at this time to make our experience 
available to other librarians who may be 
considering the use of this system. 

W e wish we could answer all the ques-
tions that have been raised about co-
ordinate indexing in the literature. 
Many earnest librarians with very con-
siderable professional experience have 
been deeply troubled by its potential pit-
falls. Perhaps we have been very lucky. 
Perhaps the pitfalls will vanish in any 
other large-scale test. W e d o not know. 
W e can report only that our system 
works. W e do not know of any other 
means to gain such tight control of large 
masses of documents so economically and 
rapidly. 

T h e r e have been problems, however; 
a n d some of them were formidable. O u r 
version of the Uniterm system of coor-
dinate indexing is certainly not the last 
word in desirable development. It con-
tains some of the whimsical invention 
a n d much of the rough-and-ready crudi-
ties of Henry Ford's Model " T " auto-
mobile. But, like the Model " T , " it runs. 
As will be a p p a r e n t in the account that 
follows, we have had to introduce many 

adaptations and changes of the system 
as originally outlined in the literature. 
Since we were pioneering, matching our 
wits against the new system day by day 
has been challenging. W e hope that in 
solving our own problems we have made 
a contribution to the developing science 
of documentation. 

F o r a n y r e a d e r u n f a m i l i a r w i t h t h e 
U n i t e r m s y s t e m of c o o r d i n a t e i n d e x i n g , 
t h e s c h e m e is c o n c e i v e d a s f o l l o w s : T h e 
i d e a s p r e s e n t e d i n t h e t i t l e of a d o c u -
ment, plus additional ideas embodied in 
the text if t h e t i t l e is n o t s u f f i c i e n t l y d e -
s c r i p t i v e , a r e b r o k e n u p i n t o s e p a r a t e 
w o r d s , d u b b e d " u n i t e r m s . " T h e d o c u -
m e n t is a s s i g n e d a n a r b i t r a r y n u m b e r . A 
5 " x 8 " m a s t e r i n d e x c a r d is p r e p a r e d 
f o r e a c h U n i t e r m , a n d t h e n u m b e r as-
s i g n e d t o a d o c u m e n t is r e g i s t e r e d o n a l l 
of t h e U n i t e r m c a r d s t h a t d e s c r i b e t h a t 
d o c u m e n t . T h u s , t h e U n i t e r m c a r d b e a r -
i n g t h e h e a d i n g C A T A L O G w i l l h a v e i n -
s c r i b e d o n i t t h e d o c u m e n t n u m b e r o f 
e v e r y r e p o r t h a v i n g a n y t h i n g of m o m e n t 
t o d o w i t h c a t a l o g s o r c a t a l o g i n g . A d o c -
u m e n t t h a t is a c a t a l o g of s p a r e p a r t s f o r 
a u t o m o b i l e w i n d s h i e l d w i p e r s w i l l h a v e 
i t s n u m b e r r e c o r d e d o n e a c h of t h e f o l -
l o w i n g c a r d s : C A T A L O G , A U T O M O B I L E , 
W I N D S H I E L D , W I P E R , P A R T S . T O f i n d t h i s 
d o c u m e n t , t h e a b o v e c a r d s a r e c o m -
p a r e d . W h e r e v e r t h e i d e n t i c a l n u m b e r 
a p p e a r s o n t w o o r m o r e c a r d s , t h a t n u m -
b e r r e p r e s e n t s a d o c u m e n t w h e r e i n t h e 
i d e a s i n t e r s e c t , i.e., c o o r d i n a t e . 

W e thought our first problem was t h e 
creation of a list of these uniterms for 
our subject matter. Here, however, o u r 
experience recommends three immedi-

JANUARY, 1956 19-



ate departures f r o m the system as pro-
posed by Documentation, Inc. 

1. Let the documents themselves gen-
erate their own uniterms. Catalog 1,000 
documents. T h e y will produce about 
1,000 uniterms. Weed this list carefully, 
combining synonyms. W i t h this core, 
catalog another 1,000 reports, using the 
"approved" basic list where possible, and 
then repeat the weeding operation. Once 
some 8,000 uniterms have been chosen, 
the rate of addition falls off very rapid-
ly, even in highly varied subject matter. 
T h e curve begins to grow nearly flat 
when between 40,000 a n d 50,000 docu-
ments have been cataloged. T h e useful 
limits of a Uniterm vocabulary are so 
soon reached that above 10,000 terms 
only highly specific items, such as new 
trade names a n d e q u i p m e n t designa-
tions, need to be added. 

2. Forget all about "free" and " b o u n d " 
terms as set f o r t h in the literature of the 
subject. " B o u n d " terms almost inevita-
bly free themselves sooner or later, and 
the intermediate step serves only to 
make extra work. Multiple words, how-
ever, should be used for exact descrip-
tion of concepts, wherever the idea ex-
pressed is a unit. 

3. F r o m t h e s t a r t , u s e see a n d see also 
r e f e r e n c e s o n t h e h e a d i n g s of U n i t e r m 
c a r d s , i n a c c o r d a n c e w i t h s t a n d a r d li-
b r a r y p r a c t i c e . W e h a v e f o u n d n o o t h e r 
s a t i s f a c t o r y s o l u t i o n f o r p r o b l e m s of n e a r 
s y n o n y m s , f o r s y n o n y m s - i n - s o m e - m e a n -
i n g s of w o r d s , a n d f o r a l l t h e o t h e r p e r -
p l e x i t i e s b o r n of t h e f a c t t h a t U n i t e r m 
c o o r d i n a t e i n d e x i n g u s e s t h e l i v i n g f a b -
r i c of l a n g u a g e f o r i t s b a s e . 

O u r next problem was the discovery 
that we needed to develop satellite in-
dexes around our coordinate index. Here 
the needs of libraries will n o d o u b t dif-
fer, b u t we soon f o u n d that in the co-
ordinate index we were building a 
heavy-duty machine unsuitable for light 
work. We decided to employ traditional 
library methods for all types of docu-
ment reference questions they served 

best, a n d to t u r n to the coordinate index 
where traditional methods broke down 
when laden with the peculiar burdens 
which documents engender. T h e com-
bination of old a n d new methods has 
turned out to be an unexpectedly har-
monious arrangement. 

Problems of work flow came next. 
O u r system as it finally evolved repre-
sents the solution of a series of prob-
lems in practical operation and hence 
may be of interest. Because the approach 
lends itself so readily to r a p i d process-
ing, attention paid to "time a n d mo-
tion" pays large dividends in total pro-
duction. O u r basic requirements per-
haps differ little f r o m those of a great 
many libraries: 

A collection of at least 200,000 tech-
nical reports a n d other documents need-
ed improved information control. T h e y 
were scattered t h r o u g h o u t the organiza-
tion in several dozen informal collec-
tions. A good many individual office 
files also needed to be surveyed. Each 
collection, small and large, had been or-
ganized according to a scheme chosen 
by its compilers. No professionally built 
catalogs existed. Large numbers of dup-
licate copies of reports were known to be 
wasting file space among various collec-
tions. T h e total n u m b e r of reports to be 
processed probably approached one mil-
lion. 

T h e task was to weed out the dupli-
cates, select items from the r e m a i n i n g 
originals which were worth keeping, and 
to create an index for them without as-
sembling a definitive central collection. 
A central index was desired but a central 
file could not be contemplated: among 
the wealth of duplicates, too many 
items were u n i q u e and were required 
for f r e q u e n t reference use in the depart-
ments then holding them. 

O u r organization is built on four 
teams of three members each, with a 
support group of twelve people located 
at the central cataloging department. 
T h r e e teams operate in the "field," visit-

20 COLLEGE AND RESEARCH LIBRARIES 



i n g a n y d e s i r e d c o m p o n e n t of t h e a g e n -
cy's o r g a n i z a t i o n a n d c a t a l o g i n g i t s d o c -
u m e n t s . T h e f o u r t h , a " h o m e " t e a m , o p -
e r a t e s i n t h e c e n t r a l d e p a r t m e n t i n as-
s o c i a t i o n w i t h t h e s u p p o r t g r o u p , a n d is 
r e s p o n s i b l e s o l e l y f o r c a t a l o g i n g n e w l y 
i s s u e d r e p o r t s . E a c h t e a m h a s a " l e a d e r " 
w h o is r e s p o n s i b l e f o r i t s e n t i r e , i n d e -
p e n d e n t o p e r a t i o n , i n c l u d i n g p u b l i c r e -
l a t i o n s w i t h t h e p e o p l e w h o s e files h e is 
o r g a n i z i n g . H e is a l s o t h e U n i t e r m c a t a -
l o g e r f o r h i s t e a m . H e is a s s i s t e d b y a 
d e s c r i p t i v e c a t a l o g e r a n d b y a c l e r k . 

A t t h e b e g i n n i n g of t h e o p e r a t i o n p e r -
f o r m e d o n a n y file d r a w e r of d o c u m e n t s , 
t h e c l e r k of t h e t e a m c o p i e s o n l y t h e ti-
t l e s i n i n f o r m a l l i s t s . O n c e d a i l y h e r e -
t u r n s t o c h e c k t h e s e a g a i n s t t h e a u t h o r i -
t y t i t l e f i l e i n t h e c e n t r a l c a t a l o g d e p a r t -
m e n t . D u p l i c a t e s of d o c u m e n t s a l r e a d y 
c a t a l o g e d a r e n o t e d . U p o n r e t u r n i n g t o 
h i s t e a m , t h e c l e r k r u b b e r - s t a m p s t h e s e 
i t e m s " D u p l i c a t e C o p y . " H e n c e f o r w a r d , 
t h e s e m a y b e d e s t r o y e d w i t h c o n f i d e n c e 
w h e n n o l o n g e r n e e d e d l o c a l l y . T h e r e -
m a i n d e r a r e s t a m p e d " R e c o r d C o p y " 
w i t h a s p a c e p r o v i d e d f o r r e g i s t e r i n g a 
p e r m a n e n t i n d e x n u m b e r . T h e s e o r i g -
i n a l s p r o v i d e t h e t e a m w i t h t h e m a t e r i a l 
f o r t h e e n s u i n g d a y ' s w o r k . 

B e c a u s e d e s k s p a c e is u s u a l l y l i m i t e d 
i n t h e office b e i n g v i s i t e d , e a c h t e a m is 
r e s t r i c t e d t o o n e t y p e w r i t e r , n o r m a l l y 
o p e r a t e d b y t h e d e s c r i p t i v e c a t a l o g e r . 
T h e d e s c r i p t i v e c a t a l o g i n g is p e r f o r m e d 
d i r e c t l y o n f a n f o l d s . B e c a u s e of t h e to-
t a l n e e d s of t h e s y s t e m , t h e p r o c e s s is 
s i m p l e a n d s w i f t . W e r e c o r d (a) t i t l e , 
( b ) c o r p o r a t e a u t h o r , (c) p e r s o n a l a u -

t h o r , ( d ) s e r i e s n u m b e r , (e) c o n t r a c t 
n u m b e r , if a n y , (f) c o l l a t i o n . N o t r a c -
i n g s , s u b j e c t h e a d i n g s , o r o t h e r t i m e -
c o n s u m i n g n o t a t i o n s a r e r e q u i r e d . T h e y 
a r e c a r e d f o r , u s i n g s i m p l e s h o r t c u t s , 
e l s e w h e r e i n t h e s y s t e m . 

D o c u m e n t a n d f a n f o l d a r e t h e n p a s s e d 
t o t h e t e a m l e a d e r , w h o v e r i f i e s t h e ac-
c u r a c y of t h e d e s c r i p t i v e c a t a l o g i n g . H e 
s c a n s , s t u d i e s , o r d i s s e c t s t h e d o c u m e n t 
as i t s i m p o r t a n c e o r d i f f i c u l t y s e e m s t o 

r e q u i r e , a n d w r i t e s o u t i n l o n g h a n d i n a 
s p a c e p r o v i d e d o n t h e f a n f o l d a l l t h e 
u n i t e r m s h e b e l i e v e s t h e d o c u m e n t r e -
q u i r e s f o r i n d e x i n g " i n d e p t h . " T h i s 
m e a n s t h a t h e a t t e m p t s t o r e c o r d all of 
t h e s u b j e c t s c o n c e r n i n g w h i c h t h i s d o c -
u m e n t c o u l d c o n c e i v a b l y b e u s e f u l . A l -
w a y s , if t h e d o c u m e n t c o n c e r n s s o m e 
s u b o r d i n a t e t o p i c — a p a r t of a l a r g e r 
m a c h i n e , a s t e p i n a p r o c e s s — t h e n e x t 
l a r g e r c o n c e p t is s e t d o w n as t h e first 
U n i t e r m . T h e n c o m e a l l t h e w o r d s t h a t 
a n s w e r t h e c l a s s i c r e p o r t e r ' s q u e s t i o n s : 
" W h o ? " " W h a t ? " " W h y ? " " W h e n ? " 
" W h e r e ? " " H o w ? " T h e n , u n i t e r m s t o 
c o v e r a n y i d e a s g i v e n s p e c i a l t r e a t m e n t 
i n t h e d o c u m e n t o r w h i c h a r e i m p o r t a n t 
i n t h e c o n c l u s i o n s . T h e t e a m l e a d e r is 
n o t a f r a i d t o s c r i b b l e o u t a l o n g l i s t . H e 
k n o w s (a) t h a t t h e e n s u i n g p r o c e s s e s i n 
i n d e x i n g t h e s e t e r m s i n t o t h e s y s t e m a r e 
so e c o n o m i c a l of t i m e t h a t i t is d e s i r a -
b l e t o e r r o n t h e s i d e of o v e r - c o m p l e t e -
n e s s , a n d ( b ) t h a t o n a n y w e e k ' s w o r k 
h i s l i s t s of u n i t e r m s w i l l a v e r a g e n i n e 
t e r m s p e r d o c u m e n t . 

H a v i n g f i n i s h e d h i s l i s t , h e e x a m i n e s 
i t c r i t i c a l l y . T h e b e s t t e s t w e h a v e f o u n d 
f o r g o o d u n i t e r m i n g is t h i s : D o t h e 
w o r d s , r e a d c o n s e c u t i v e l y , c o m e c l o s e t o 
f o r m i n g a c o m p l e t e a n d i n t e l l i g i b l e s e n -
t e n c e ? If so, n o e s s e n t i a l h a s p r o b a b l y 
b e e n o m i t t e d . N e x t q u e s t i o n : D o t h e 
t e r m s c o v e r a l l t h e i d e a s f o r w h i c h t h i s 
d o c u m e n t c o u l d b e w a n t e d ? H e r e , of 
c o u r s e , t h e h u m a n f a c t o r e n t e r s h e a v i l y 
— t h e c a t a l o g e r ' s k n o w l e d g e , b a c k -
g r o u n d , a n d p l a i n b r a i n p o w e r . W e 
k n o w of n o o t h e r s y s t e m , h o w e v e r , w h e r e 
o v e r l y - c a r e f u l a n d t o o - d e t a i l e d i n d e x i n g 
c a n b e so c h e e r f u l l y a p p l a u d e d b y t o p 
m a n a g e m e n t . I t is c e r t a i n l y t r u e t h a t 
p e r f e c t l y s a t i s f a c t o r y i n d e x i n g c a n b e 
p e r f o r m e d b y c a t a l o g e r s w i t h m u c h i n -
f e r i o r t e c h n i c a l s u b j e c t b a c k g r o u n d t h a n 
is r e q u i r e d i n a n y t a x o n o m i c s y s t e m of 
c l a s s i f i c a t i o n . 

T h e t e a m l e a d e r ' s final c h o r e is t o as-
s i g n a p e r m a n e n t a c c e s s i o n n u m b e r t o 
t h e d o c u m e n t a n d t o r e c o r d i t o n b o t h 

JANUARY, 1956 21-



d o c u m e n t a n d f a n f o l d . H e c h o o s e s t h i s 
n u m b e r f r o m a b l o c k of " o p e n " n u m -
b e r s c u r r e n t l y a s s i g n e d f o r h i s u s e . W h e n 
t h e d o c u m e n t is r e f i l e d b y h i s c l e r k , h i s 
p a r t of t h e o p e r a t i o n is c o m p l e t e d . 

T h e r o u t i n e i n t h e c e n t r a l office e m -
p l o y s c o p i e s of t h e f a n f o l d s f o r v a r i o u s 
n e e d s . T h e o r i g i n a l a n d o n e c a r b o n g o 
f i r s t t o t h e U n i t e r m c o n t r o l o f f i c e r , w h o 
m u s t a p p r o v e a l l n e w t e r m s , a d j u s t c r o s s 
r e f e r e n c e s , a n d e l i m i n a t e u s e l e s s s y n o -
n y m s . T h e o r i g i n a l t h e n g o e s t o t h e 
c l e r k w h o t y p e s t h e M u l t i l i t h s t e n c i l s , 
a n d finally t o t h e d e s k w h e r e t h e b i -
w e e k l y d o c u m e n t a c c e s s i o n s l i s t is p r e -
p a r e d . T h e c a r b o n is r o u t e d t o t h e p o s t -
i n g c l e r k s . T h e s e c o n d c a r b o n is f i l e d 
i m m e d i a t e l y i n t h e t i t l e a u t h o r i t y f i l e ; 
t h e t h i r d i n t h e a c c e s s i o n - n u m b e r f i l e 
u n t i l r e p l a c e d b y t h e p e r m a n e n t p r i n t e d 
c a r d . 

F o r e c o n o m y , s t e n c i l s a r e c u t w i t h a 
m i c r o - e l i t e t y p e w r i t e r o n c o m m e r c i a l l y 
a v a i l a b l e M u l t i l i t h m a t s of n a r r o w g a u g e 
h a v i n g p e r f o r a t e d s p r o c k e t e d g e s w h i c h 
p r e v e n t s l i p p i n g , s i n c e t h e t y p e w r i t e r is 
e q u i p p e d ( a t v e r y s m a l l c o s t ) w i t h 
s p r o c k e t g u i d e s a b o v e t h e p l a t e n . W h e n 
t h e s e s p r o c k e t e d g e s a r e t o r n off a l o n g 
t h e p e r f o r a t i o n , t h e s t e n c i l is t h e c o r r e c t 
w i d t h t o p r i n t 3 " x 5 " c a r d s o n l o n g 
s h e e t s . T h e p r e s s w i l l a c c o m m o d a t e t w o 
of t h e s e m a s t e r s s i d e b y s i d e s o t h a t p r e s s 
t i m e is r e d u c e d t o h a l f . T h e s t e n c i l s a r e 
p r e - p r i n t e d , a g a i n f o r e c o n o m y , w i t h 
w h a t e v e r l e g e n d s a r e s t a n d a r d f o r t h i s 
l i b r a r y ' s c a r d s . T h e f i n i s h e d s h e e t s of 
p r i n t e d c a r d s , b e i n g c o m p l e t e l y u n i f o r m 
i n r e g i s t e r , c a n b e m a c h i n e c u t , r e a d y f o r 
f i l i n g . S a t e l l i t e f i l e s a r e m a i n t a i n e d b y 
t i t l e , c o r p o r a t e a u t h o r , p e r s o n a l a u t h o r , 
s e r i e s n u m b e r , a n d c o n t r a c t n u m b e r . 

T h e " p o s t i n g " o p e r a t i o n , a s t h e p r o c -
ess of r e c o r d i n g d o c u m e n t n u m b e r s o n 
U n i t e r m c a r d s is c a l l e d , c a u s e d r e a l t r o u -
b l e . H e r e l a y t h e m o s t f o r m i d a b l e p r o b -
l e m w e e n c o u n t e r e d i n t h e a p p l i c a t i o n 
of c o o r d i n a t e i n d e x i n g . T h e p r o c e s s 
s e e m s s i m p l e e n o u g h , b u t o n c e i t is b e -
g u n d i f f i c u l t i e s m u l t i p l y . E a c h c a r d m u s t 

b e p u l l e d , r e c o r d e d u p o n , a n d r e f i l e d . 
T h e w o r k is b o r i n g a n d f a t i g u i n g . E r -
r o r s a r e e a s y t o m a k e a n d d i f f i c u l t t o d e -
t e c t . W o r k e r s g e t i n e a c h o t h e r ' s w a y . 
W h i l e p o s t i n g is g o i n g o n , a n y r e f e r -
e n c e u s e of t h e i n d e x u s u a l l y m e a n s t h a t 
o n e o r t h e o t h e r o p e r a t i o n m u s t s t o p . 
P o s t i n g w a s h o p e l e s s l y s l o w i n r e l a t i o n t o 
t h e s m o o t h n e s s a n d s p e e d d i s p l a y e d i n 
a l l o t h e r s t e p s . I t is n o t a n e x a g g e r a t i o n 
t o say t h a t t h i s b o t t l e n e c k t h r e a t e n e d t h e 
c o l l a p s e of o u r e n t i r e s y s t e m . 

T h e s o l u t i o n p r o v e d t o b e a s i m p l e 
o n e . W e i n s t a l l e d a n I B M p u n c h i n t h e 
c a t a l o g d e p a r t m e n t a n d e q u i p p e d i t w i t h 
t w o s t a n d a r d " p r o g r a m s . " A d o c u m e n t 
n u m b e r p u n c h e d ( a n d v e r i f i e d ) o n t h e 
f i r s t c a r d is a u t o m a t i c a l l y r e p r o d u c e d o n 
a l l e n s u i n g c a r d s u n t i l t h e o p e r a t o r 
w i s h e s t o c h a n g e i t . I n c h a n g i n g f r o m 
o n e d o c u m e n t n u m b e r t o t h e n e x t h i g h -
e r o n e , t h e o p e r a t o r t o u c h e s o n l y t h e 
f i n a l d i g i t k e y s . O n e t y p i s t w o r k i n g t w o 
h o u r s a d a y c a n k e e p u p w i t h t h e p u n c h -
i n g f r o m a l l f a n f o l d s g e n e r a t e d b y a l l 
f o u r t e a m s w o r k i n g a t f u l l p r o d u c t i o n . 
A t t h e e n d of e a c h w e e k t h e a c c u m u l a t e d 
I B M c a r d s a r e d r o p p e d i n t o a m a c h i n e 
s o r t e r . 

N o w t h e p o s t i n g o p e r a t i o n is a q u i t e 
d i f f e r e n t m a t t e r . O u r c o o r d i n a t e i n d e x 
is h o u s e d i n t h e f a m i l i a r l i b r a r y " K a r -
d e x " t y p e file. B e g i n n i n g w i t h t h e f i r s t 
o n e r e q u i r e d , t h e p o s t e r w i t h d r a w s o n e 
t r a y a t a t i m e , d i s t u r b i n g r e f e r e n c e w o r k -
e r s a n d o t h e r p o s t e r s n o m o r e t h a n d o e s 
a n y o t h e r c a t a l o g d e p a r t m e n t w o r k e r 
w h e n s h e r e m o v e s a d r a w e r f r o m t h e m a i n 
c a r d c a t a l o g i n a n y l i b r a r y t o file a n e w 
c a r d . O n t h e U n i t e r m c a r d f o r A U T O M O -
B I L E t h i s c l e r k p o s t s t h e n u m b e r f o r t h e 
d o c u m e n t o n w i n d s h i e l d w i p e r s , and all 
others concerned with automobiles that 
the library has cataloged that week. T h e 
I B M s o r t i n g m a c h i n e h a s e v e n p l a c e d a l l 
t h e a u t o m o b i l e e n t r i e s i n c o r r e c t n u m e r -
i c a l o r d e r . T h e p o s t i n g o p e r a t i o n is s w i f t 
a n d h i g h l y a c c u r a t e . 

W e h a d o u r fingers c r o s s e d c o n c e r n i n g 
t h e r e a c t i o n of o u r l i b r a r y u s e r s t o w a r d 

22 COLLEGE AND RESEARCH LIBRARIES 



the coordinate index, b u t we soon dis-
covered that our misgivings were 
groundless. Unless this agency's em-
ployees are miraculously different f r o m 
the general public, no one else needs 
to worry either. It is true, however, that 
the most enthusiastic response has been 
from our engineers and others with 
training in some academic discipline. 
Use of the system numbers several hun-
dred questions each week. 

O n the premise that our customers 
could not care less whether the answer 
to their reference question came f r o m a 
book, a serial, or a document, we placed 
the coordinate index and its satellite 
catalogs right beside the library card 
catalog. All who will may use them. 
H a b i t u a l library customers almost in-
variably prefer to consult the coordinate 
index unaided after their first five-min-
ute indoctrination course in the system. 
Reference personnel are available, of 
course, to help any newcomer, or any-
one else with a problem. W e think it is 
sound public relations to offer to help 
everyone. Everyone, including the ref-
erence staff, is taught to think of the co-
ordinate index as his heavy artillery. 
Where author, title, or serial n u m b e r of 
a document is known, the satellite cata-
logs provide quick reference. 

Much has been printed speculating on 
the a m o u n t of "noise" a large installa-
tion of coordinate indexing would pro-
duce; that is, the n u m b e r of false co-
ordinations of the man-bites-dog variety 
which would interfere with effective re-
search work. T h e gloomy predictions 
have not been borne out by our year of 
operational use of the system. Now, it 
may well be that there are subject fields 
in which "false hits" would embarrass 
the reference librarian. W e can only re-
port that, in our library, a little care a n d 
forethought in the catalog d e p a r t m e n t 
has kept the n u m b e r of false coordina-
tions so small, in our subject matter, 
that the annoyance is negligible. W e 
have f o u n d that: (a) the more specific 

the subject field we are cataloging the 
tighter is the information control 
gained; (b) the more specific the uni-
terming the fewer are the false hits cre-
ated; (c) skillful uniterming is a logical 
fractionating process, not a mere slicing 
of a document's title into separate words 
—this is especially true in the exact 
sciences; (d) wherever the man-bites-
dog difficulty can be foreseen by a cata-
loger, the addition of a simple delta sign 
after the index word will signal the ref-
erence user which one is the correct 
reading, e.g., G E R M A N Y A — I M P O R T S — 
F R A N C E means only German imports 
f r o m France, not French imports f r o m 
Germany. W e have used these "delta 
flags" freely for words which cause us 
trouble. T h e i r total number, however, 
has remained small. 

T h e r e are, no doubt, more problems 
which we shall encounter as time goes 
on, b u t these are all the difficulties which 
we have met so far. A potential problem, 
that of an unwieldy pile u p of numbers 
on " p o p u l a r " uniterms, was solved just 
as it arose with us by a timely p a p e r 
from the Office of Basic Instrumenta-
tion of the U. S. National Bureau of 
Standards.1 O n the question of "brows-
ability" of the system we refer the reader 
to the excellent discussion of "brows-
ability and suggestability" in the same 
paper. I n their conclusions we heartily 
concur. 

W e have discovered no completely 
valid method to test the reliability, or 
the percentage of completeness of re-
trieval of information, of our index. W e 
can testify that to date it has never failed 
to produce any "known" document. T h e 
expressions of pleasure we receive con-
cerning the quality of our reference 
service leads us to conclude that the per-
centage of retrieval is high, perhaps even 
very high. 

1 W i l l i a m W i l d h a c k , a n d o t h e r s , " D o c u m e n t a t i o n 
i n I n s t r u m e n t a t i o n , " American Documentation, V 
( 1 9 5 4 ) , 223-37. T h i s a r t i c l e c o n t a i n s a u s e f u l b i b l i o g -

r a p h y o n d o c u m e n t a t i o n e x p e r i m e n t s r e p o r t e d a b r o a d . 
W e e m p l o y s t a n d a r d U n i t e r m c a r d s f o r all e x c e p t 
t h e m o s t h e a v i l y u s e d t e r m s . 

JANUARY, 1956 23-