nelsonted_complexinformationproces_77793

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AUG. 24/11:00 12:30/GO LD ROOM

S E S S IO N 4 : C o m p l e x I n fo r m a t i o n P r o c e s s in g

4 . 2 : A F i le S t r u c t u r e f o r T h e C o m p l e x , T h e C h a n g i n g a n d t h e I n d e t e r m i n a t e

T . H . N e l s o n

V a s s a r C o l le g e , P o u g h k e e p s i e ,N . Y .

T H E K I N D S O F F I L E s t r u c t u r e s r e q u i r e d i f w e a r e t o u se t h e c o m p u t e r f o r p e r s o n a l

f i l e s a n d as a n a d j u n c t t o c r e a t i v i t y a r e w h o l l y d i f f e r e n t i n c h a r a c t e r f r o m t h o s e

c u s t o m a r y i n b u s i n e s s a n d s c i e n t i f i c d a t a p r o c e s s i n g . T h e y n e e d to p r o v i d e t h e

c a p a c i t y f o r i n t r ic a t e a n d i d i o s y n c r a t i c a r r a n g e m e n t s , t o t a l m o d i f i a b i l i t y , u n d e -

c i d e d a l t e r n a t i v e s , a n d t h o r o u g h i n t e r n a l d o c u m e n t a t i o n .

The origin al idea was to make a file for writ ers and scientists, muc h like

t h e p e r s o n a l s i d e o f B u s h ' s M e m e x , t h a t w o u l d d o t h e t h i n gs s u c h p e o p l e n e e d w i t h

t h e r i c h n e s s t h e y w o u l d w an t . B u t t h e r e a r e s o m a n y p o s s i b l e s p e c i f i c f u n c t i o n s

t h a t t he m i n d r e e l s . T h e s e u s e s a n d c o n s i d e r a t i o n s b e c o m e s o c o m p l e x t h a t th e

o n l y a n s w e r is a s i m p l e a nd g e n e r a l i z e d b u i l d i n g - b l o c k s t r u c t u r e , u s e r - o r i e n t e d a n d

w h o l l y g e n e r a l - p u r p o s e .

The result ing file structure is explai ned and example s of its use are given.

I t b e a r s g e n e r i c s i m i l a r i t i e s t o l i s t - p r o c e s s i n g s y s t e m s b u t i s s l o w e r a nd b i g g er .

I t e m p lo y s z i p p e r e d l i s ts p l u s c e r t a i n f a c i l i t i e s f o r m o d i f i c a t i o n a n d s p i n - o f f o f

v a r i a t i o n s . T h i s i s t e c h n i c a l l y a c c o m p l i s h e d b y i n d e x m a n i p u l a t i o n a n d te x t p a t c h -

i n g , bu t t o t h e u s e r i t a ct s l i ke a m u l t i f a r i o u s , p o l y m o r p h i c , m a n y - d i m e n s i o n a l ,

i n f i n i t e b l a c k b o a r d .

T h e r a m i f i c a t i o n s o f t h is a p p r o a c h e x t e n d w e l l b e y o n d i t s o r i g i n a l c o n c e r n s ,

i n t o s u c h p l a c e s a s i n f o r m a t i o n r e t r i e v a l a n d l i b r a r y s c i e n c e , m o t i o n p i c t u r e s a n d

t h e p r o g r a m m i n g c r a ft ; f o r it i s a l m o s t e v e r y w h e r e n e c e s s a r y t o d e a l w i t h d e e p

struc tural chan ges in the arran gemen ts of ideas and things.

I want to expl ain how some ideas developed and what they are. The origina l

p r o b l e m w a s t o s p e c i f y a c o m p u t e r s y s t e m f o r p e r s o n a l i n f o r m a t i o n r e t r i e v a l a n d

d o c u m e n t a t i o n , a b l e t o d o s o m e r a t h e r c o m p l i c a t e d t h i n g s i n c l e a r an d s i m p l e w ay s .

T h e i n v e s t i g a t i o n g a t h e r e d g e n e r a l i t y , h o w e v e r , a n d h a s e v e n t u a t e d i n a n u m b e r o f

ideas. These are an info rmati on structu re, a file structur e, and a file language,

e a c h p r o g r e s s i v e l y m o r e c o m p l i ca t e d . T h e i n f o r m a t i o n s t r u c t u r e I c a l l z i p p e r e d

lists; the file s tru ctu re is the ELF, or ]Evolutionary Lis't File; and the file lan-

guage (proposed) is called PRIDE.

I n t h is p a p e r I w i l l e x p l a i n t h e o r i g i n a l p r o b l e m . T h e n I w i l l e x p l a i n w h y

the prob lem is not simple, and why the solut ion (a file structure) m ust yet be

v e r y s i m p le . T h e f i l e s t r u c t u r e s u g g e s t e d h e r e i s t h e E v o l u t i o n a r y L i s t F i l e , t o

be built of zippered lists. A numbe r of uses will be suggeste d for such a file, to

s h o w t h e b r e a d t h o f it s p o t e n t i a l u s e f u l n e s s . F i n a l l y , I w a n t t o e x p l a i n t he

p h i l o s o p h i c a l i m p l i c a t i o n s o f t h i s a p p r o a c h f o r i n f o r m a t i o n r e t r i e v a l a n d d a t a

s t r u c t u r e i n a c h a n g i n g w or l d .

8 4 A C M 2 0 t h N a t i o n a l C o n f e r e n c e / 1 9 6 5


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T h i s w o r k wa s b e g u n i n 1 9 6 0 - w i t h o u t a n y a s s i s t a n c e . I t s p u r p o s e w a s t o

c r e a t e t e c h n i q u es f o r h a n d l i n g p e r s o n a l f i l e s y s t e m s a n d m a n u s c r i p t s i n p r o g r e s s .

T h e s e t w o p u r p o s e s a r e c l o s e l y r e l a t e d a n d n o t s h a r p l y d i s t i n c t . M a n y w r i t e r s a n d

r e s e a r c h p r o f e s s i o n a l s h a v e f i l e s o r c o l l e c t i o n s o f n o t e s w h i c h a r e t i e d t o m a n u -

s c r i p t s i n p r o g r e s s . I n d e e d , o f t e n p e r s o n a l f i l e s s h a d e in t o m a n u s c r i p t s , a n d t h e

a s s e m b l y o f t e x t u a l n o t e s b e c o m e s t h e w r i t i n g o f t e x t w i t h o u t a s h ar p b r e a k .

I k n e w f r o m m y o w n e x p e r i m e n t w h a t c a n b e d o n e f o r t h e s e p u r p o s e s w i t h c a r d

f i l e , n o t e b o o k , i n d e x t a b s, e d g e - p u n c h i n g , f i l e f o l d e r s , s c i s s o r s a n d p a s t e ,

g r a p h i c b o a rd s , i n d e x - s t r i p f r a me s , X e r o x m a c h i n e a n d t h e r o l l - t o p d e s k . M y i n-

t e n t w a s n o t m e r e l y t o c o m p u t e r i z e t h e s e t a s k s b u t t o t h i n k o u t ( a n d e v e n t u a l l y

p r o g r a m ) t h e d r e a m fi l e: t h e f i l e s y s t e m t h a t w o u l d h a v e e v e r y f e a t u r e a n o v e l i s t

o r a b s e n t - m i n d e d p r o f e s s o r c o u l d w a n t , h o l d i n g e v e r y t h i n g h e w a n t e d i n j u s t t h e

c o m p l i c a t e d w a y h e w a n t e d i t h e l d , a n d h a n d l i n g n o t e s a n d m a n u s c r i p t s i n a s s u b t le

a n d c o m p l e x w a y s a s he w a n t e d t h e m ha n d l e d .

O n l y a f e w o b s t a c l e s i m p e d e o u r u s i n g c o m p u t e r - b a s e d s y s t e m s f o r t h e s e pu r -

p o s e s . T h e s e h a v e b e e n h i g h c o s t , l i t t l e s e n s e o f n e e d , a n d u n c e r t a i n t y a b o u t s y s -

t e m d e s i g n .

T h e c o st s a r e n o w d o w n c o n s i d e r a b ly . A s ma l l c o m p u t e r w i t h m a s s m e m o r y a n d

v i d e o - t y p e d i s p l a y n o w c o s t s $ 3 7 , 0 0 0; a m o r t i z e d o v e r t i m e t hi s w o u l d c o s t l e ss t h a n

a s e c r e t a r y , a n d s e v e r a l p e o p l e c o u l d u s e i t a r o u n d t h e c l o c k . A l a r g e r i n s t a l l a -

t i o n s e r v i c i n g a n e d i t o r i a l o f f i c e o r a n e w s p a p e r m o r g u e , o r a d o z e n s c i e n t i s t s o r

s c h o l a r s , c o u l d c o s t p r o p o r t i o n a t e l y l e s s a n d g i v e m o r e t i m e t o e a c h u s er .

T h e s e c o n d o b s t a c l e , s e n s e o f n e e d , I s a m a t t e r o f fa s h i o n . D e s p i t e c h a n g -

i n g e c o n o m i e s, i t i s f a s h i o n a b l y b e l i e v e d t h a t c o m p u t e r s a r e p o s s e s s e d o n l y b y

h u g e o r g a n i z a t i o n s t o b e u s e d o n l y f o r v a s t c o r p o r a t e t a s k s o r i n t r i c a t e s c i e n t i f i c

c a l c u l a t i o n s . A s l o n g a s p e o p l e t h i n k t ha t , m a c h i n e s w i l l b e b r u t e s a n d n o t

f r i e n d s , b u r e a u c r a t s a n d n o t h e l p m a t e s . B u t s i n c e ( a s I w i l l i n d i c a t e ) c o m p u t e r s

c o u l d d o t h e d i r t y w o r k o f p e r s o n a l f i l e a n d t e x t h a n d l i n g , a n d d o it w i t h r i c h -

n e s s a n d s u b t l e t y b e y o n d a n y t h i n g w e k n o w , t h e r e o u g h t t o b e a s e n s e o f n e e d . U n -

f o r t u n a t e l y , t h e r e a re n o a s c e r t a i n a b l e s t a t i s t i c s o n t h e a m o u n t o f t i m e w e w a s t e

f u s s i n g a mo n g p a p e r s a n d m i s l a y i n g t h i ng s . S u r e l y h a l f t h e ti m e s pe n t i n w r i t i n g

i s s p e n t p h y s i c a l l y r e a r r a n g i n g w o r d s a n d p a p e r a n d t r y i n g t o f i n d t hi n g s a l r e a d y

w r i t t e n ; i f 9 5 % o f t hi s t i m e c o u l d b e s a v e d , i t w o u l d o n l y t a k e h a l f a s l o n g t o

w r i t e s o m e t h i n g .

T h e t h i r d o b s t a c l e , d e s i g n , i s t h e o n l y s u b s t a n t i v e o n e , t h e o n e t o w h i c h

t h i s p a p e r s p e a k s .

L e t m e s p e a k f i r s t o f t h e a u t o m a t i c p e r s o n a l f i l i n g s y s t e m . T h i s i d e a i s b y

n o m e a n s n e w . T o go b a c k o n l y a s f ar a s 1 9 4 5 , V a n n e v a r B u s h , i n h i s f a m o u s a r t i c l e

A s W e M a y T h i n k l , d e s c r i b e d a s y s t e m o f t h i s t y p e. B u s h ' s p a p e r i s b e t t e r r e -

m e m b e r e d f o r i t s p r e d i c t i o n s i n t h e f i e l d o f i n f o r m a t i o n r e t r i e v a l , a s h e f o r e s a w

t h e s p r e a d a n d p o w e r o f a u t o m a t i c d o c u m e n t h a n d l i n g a n d t h e m a n y n e w i n d e x i n g

t e c h n i q u e s i t w o u l d n e c e s s i t a t e . B u t n o t e h i s p r e d i c t i o n s f o r p e r s o n a l f i l i n g :

C o n s i d e r a f u t u r e d e v i c e f o r i n d i v i d u a l u s e , w h i c h i s a s o r t o f

m e c h a n i z e d p r i v a t e f i l e a nd l i b r a r y . I t n e e d s a n a m e , a n d , t o c o i n o n e

a t r a n d o m , m e m e x w i l l do . A m e m e x i s a d e v i c e i n w h i c h a n i n d i v i d u a l

stor es all his books , rec ords, and con~nunications, and whi ch is

P R O C E E D I N G S 8 5


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m e c h a n i z e d s o t ha t i t m a y b e c o n s u l t e d w i t h e x c e e d i n g s p e e d a n d f l e x -

i b i l i t y . I t is a n e n l a r g e d i n t i m a te ~ s u p p l e m e n t t o h i s m e m o r y .

I t c o n s i s t s o f a d e s k , a n d w h i l e i t c a n p r e s ~ m e b l y b e o p e r a t e d

f r o m a d i s t a n c e , i t i s p r i m a r i l y t h e p i e c e o f f u r n i t u r e a t w h i c h h e

w o r k s . O n t h e t o p a r e s l a n t i n g t r a n s l u c e n t s c r e e n s , o n w h i c h m a t e r i a l

c a n b e p r o j e c t e d f o r c o n v e n i e n t r e a d i n g . T h e r e i s a k e y b o a r d , a n d s e t s

o f b u t t o n s a n d l e v e r s . O t h e r w i s e i t l o o k s l ik e a n o r d i n a r y d e s k .

A s p e c i a l b u t t o n t r a n s f e r s h i m i m m e d i a t e l y t o t h e f i rs t p a g e o f

t h e i n d e x. A n y g i v e n b oo k_ o f h i s l i b r a r y / _a n d p r e s u m a b l y o t h e r t e x t u a l

m a t e r i a l , s u c h a s n o t e s / c a n t h u s b e c a l l e d u p a n d c o n s u l t e d w i t h f a r

g r e a t e r f a c i l i t y t h a n i f i t w e r e t a k e n f r o m a s h e l f . A s h e h a s s e v e r a l

p r o j e c t i o n p o s i t i o n s , h e c a n l e a v e on e i t e m i n p o s i t i o n w h i l e h e c a l l s

u p a n o t h e r . H e c a n a d d m a r g i n a l n o t e s a n d c o m m e n t s , . . . . ( i, 1 0 6 - 7 )

U n d e r s t a n d i n g t h a t s u c h a m a c h i n e r e q u i r e d n e w k i n d s o f f i l i n g a r r a n g e m e n t s , B u s h

s t r e s s e d h i s f i l e ' s a b i l i t y t o s t o r e r e l a t e d m a t e r i a l s i n a s s o c i a t i v e t r a i l s ,

l i s t s o r c h a i n s o f d o c u m e n t s j o i n e d t o g e t h e r .

W h e n t h e u s e r i s b u i l d i n g a t r ai l , h e n a m e s i t , i n s e r t s t h e

n a m e i n h i s c o d e b o o k , a n d t a p s it o u t o n h i s k e y b o a r d . B e f o r e h i m

a r e t h e t wo i t em s t o b e j o i ne d , p r o j e c t e d o n t o a d j a c e n t v i e w i n g

p o s i t i o n s . A t t h e b o t t o m o f e a c h t h e r e ar e a n u m b e r o f b l a n k c o d e

s p a c e s , a n d a p o i n t e r i s se t t o i n d i c a t e o n e o f t h e s e o n e a c h i t e m .

T h e u s e r t a p s a s i n g l e k e y , a n d t h e i t e m s a r e p e r m a n e n t l y j o i n e d . . ..

T h e r e a f t e r , a t a n y t i m e , w h e n o n e o f t h e s e i t e m s i s i n v i e w ,

t h e o t h e r c a n b e i n s t a n t l y r e c a l l e d m e r e l y b y t a p p i n g a b u t t o n b e l o w

t h e c o r r e s p o n d i n g c o d e s p a c e . M o r e o v e r , w h e n n u m e r o u s i t e m s h a v e

b e e n t h u s j o i n e d t o g e t h e r t o f o r m a t r a i l , t h e y c a n b e r e v i e w e d i n

t u r n , r a p i d l y o r s l o w l y , b y d e f l e c t i n g a l e v e r l i k e t h a t u s e d f o r

t u r n i n g t h e p a g e s o f a b o o k . I t i s e x a c t l y a s t h o u g h t h e p h y s i c a l

i t e m s h a d b e e n g a t h e r e d t o g e t h e r f r o m w i d e l y s e p a r a t e d s o u r c e s a n d

b o u n d t o g e t h e r t o f o r m a n e w b o o k. I t i s m o r e t h a n t h i s, f o r a n y

i t e m c a n b e j o i n e d i n t o n u m e r o u s t r a i l s . . ..

T h u s h e g o e s , b u i l d i n g a t r a i l o f m a n y i t e m s. O c c a s i o n a l l y

h e i n s e r t s a c o m m e n t o f h i s o w n , e i t h e r l i n k i n g i t i n t o t h e m a i n

t r a i l o r j o i n i n g i t b y a s i d e t r a i l t o a p a r t i c u l a r i t e m . . .. ( i , 1 07 )

T w o d e c a d e s l a t e r , t h i s m a c h i n e i s s t i l l u n a v a i l a b l e * .

T h e h a r d w a r e i s r e a d y. S t a n d a r d c o m p u t e r s c a n h a n d l e h u g e b o d i e s o f w r i t t e n

i n f o r m a t i o n , s t o r i n g t h e m o n m a g n e t i c r e c o r d i n g m e d i a a n d d i s p l a y i n g t h e i r co n -

t e n t s o n C R T c o n s o l e s , w h i c h f a r o u t s h i n e d e s k t o p p r o j e c t o r s . B u t n o p r o g r a m s , n o

f i l e s o f t w a r e a r e s t a n d i n g r e a d y t o d o t h e i n t r i c a t e f i l i n g j o b ( k e e p i n g t r a c k o f

a s s o c i a t i v e t r a i l s a n d o t h e r s t K u c t u r e s ) I th at t h e a c t i v e s c i e n t i s t o r t h i n k e r

w a n t s a n d n e e d s . W h i l e W a l l a c e Z r e p o r t s t h a t t h e S y s t e m D e v e l o p m e n t C o r p o r a t i o n

h a s f o u n d i t w o r t h w h i l e t o g i v e i t s e m p l o y e e s c e r t a i n l i m i t e d c o m p u t e r f a c i l i t i e s

f o r t h e i r o w n f i l i n g s y s t e m s , t h i s i s a b a r e b e g i n n i n g .

L e t u s c o n s i d e r t h e o t h e r d e s i d e r a t u m , m a n u s c r i p t h a n d l i n g . T h e r e m a r k s

t h a t f o l l o w a r e i n t e n d e d t o a p p l y t o a l l f o r m s o f w r i t i n g , i n c l u d i n g f i c t i o n ,

p h i l o s o p h y , s e r m o n s , n e w s an d t e c h n i c a l w r i t i ng .



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The problems of writi ng are little understood, even by writers. Systems

analysis in this area is scanty; as elsewhere, the best doers may not understand

what they do. Alth ough there is considera ble anec dote and lore about the differ-

ent physical manuscri pt and file techniques of different authors, literary tradi-

tion demerits any concern with technical systems as detract ing from creativity.

(Conversely, technical people do not always apprecia te the diffi culty of organiz-

ing text, since in technical writing m uch of the organ izatio n and phraseology is

given, or appears to be.) But in the computer sciences we are profoun dly a ware of

the importance of systems details, and of the varie ty of consequences for both

qualit y and quantity of work that result from different systems. Y et to design

and evaluate systems for writing, we need to know what the process of writing is.

There are three false or inadequate theories of how writi ng is properly done.

The first is that writing is a matter of inspiration. While inspirat ion is useful,

it is rarel y enou gh in itself. Writ ing is l~/o inspi rati on, 9Y/o persp irati on, is

a common saying. But this leads us to the second false theory, that writing con-

sists of applying the seat of the pants to the seat of the chair. Insofar as

sitting facilitates work, this view seems reasonable, but it also suggests th t

what is done while sitting is a matte r of comparative indifference; probably not.

The third false theory is that all you really need is a good outline, created

on prior consider ation, and that if the outline is correctly followed the required

text will be produced. For m o s t good writers this theory is quite wrong. Rarel y

does the original outline predict well what headings and sequence will create the

effects desired: the balance of emphasis, sequence of interrelating points, texture

of insight, rhyt hm, etc. We may better call the outlini ng process inductive:

certain i nterrelati ons appear to the author in the mater ial itself, some at the

outset and some as he works. He can only decide whic h to emphasize, whic h to use

as unifying ideas and principles, and which to slight or delete, by trying. Out-

lines in general are spurious, made up after the fact by examining the segment ation

of a finished work. If a finished work cle arly follows an outline, th t o ~ l i n e

probably has been han~nered out of many inspirations, comparisons and tests .

Between the inspirations, then, and during the sitting, the task of writi ng

is one of rearrangement and reprocessing, and the real outline develops slowly.

The original ~rude or fragmentary texts created at the outset genera lly underg o

m a n y r e v i s i o n p r o c e s s e s b e f o r e t h ey a r e f i ni s h ed . I n t e l l e c t u a l l y t h e y a r e p o n d e r e ~

juxtaposed, co mpared, adapted, transposed, and judged; mecha nical ly they are

copied, overwr itten with revisio n markings, r earranged and copied again. This

cycle may be repeated many times. The whole grows by trial and error in the pro-

cesses of arrangement, compariso n and retrenchment. By examini ng and mental ly not-

ing many different versions, some whole but most fr agmentar~ l the intertwining and

o r g a n i z i n g o f t h e f i n al w r i t t e n w o r k g r a d u a l l y t a k es p l a c e ~ .

Certai n things have been done in the area of computer manuscrip t handling.

I B M r e c e nt l y a n n o u n c e d i ts A d m i n i s t r a t i v e T e r m i n a l S y s t e W ' 5 , 6 , 7 , 8 w h i c h p e r m i t s

the storage of unfinishe d sections of text in computer memory, permits various

modificatio ns by the user, and types up the final draft with page numbers, right

justifica tion and headers.

While this is a good thing, its function for manuscri pts is cosmetic rather

than organizing. Such a system can be used only with textual secti ons which are

already well organized, the visibl e part of the iceberg. The major and strenuous

part of such writing must alrea dy have been done.



5/17

If a writ er is really to be helped by an automated system, it ought to do

m o r e t h a n r e t y p e a n d t r a n s p o s e : i t s h o ul d s t a n d b y h i m d u r i n g t h e e a r l y p e r i o d s o f

m u d d l e d c o n f u s i o n , w h e n h i s i d e as a r e s c ra p s , f r a g m e n ts , p h r a s e s , a n d c o n t r a d i c t o r y

o v e r a l l d e s i g n s. A n d i t m u s t h e l p h i m t h r o u g h t o th e f i na l d r a f t w i t h e v e r y

feasible mechanic al aid-- makin g the fragments easy to find, and maki ng easier the

t e n t a t i v e s e q u e n c i n g a n d j u x t a p o s i n g a n d c o m p a r in g .

It was for these two purpose s, taken togethe r-- perso nal filing and manu-

s c r i p t a s s e m b l y - - t h a t t h e f o l l o w i n g s p e c i f i c a t i o n s w e r e d r a w n u p.

H e r e w e r e t h e p r e l i m i n a r y s p e c i f i c a t i o n s o f t h e s y s t em : I t w o u l d p r o v i d e a n

u p - t o - d a t e i n d e x o f i ts o w n c o n t e n t s ( s u p p l a n t i n g t h e c o d e b o o k s u g g e s t e d b y

B u s h ). I t w o u l d a c c e p t l a r g e a n d g r o w i n g b o d i e s o f t ex t a n d c o m m e n t a r y , l i s t e d i n

s u c h c o m p l e x f o r m s a s t he u s e r m i g h t s t i p u l a t e . N o h i e r a r c h i c a l f i l e r e l a t i o n s

w e r e t o b e b u i l t in ; t h e s y s t e m w o u l d h o l d a n y s h a p e i m p o s e d o n i t. I t w o u l d f i l e

t e x t s i n a n y f o r m a n d a r r a n g e m e n t d e s i r e d - - c o m b i n i n g , a t w i l l , t h e f u n ct i o n s o f

t h e c a r d f i le , l o o s e - l e a f n o t e b o o k , a n d s o o n. I t w o u l d f i l e u n d e r a n u n l i m i t e d

n u m b e r o f c a t e g o r i e s . I t w o u l d p r o v i d e f o r f i l i n g i n B u s h tr a i l s. B e s i d e s t h e

file entries thems elves, it woul d hold co~mnentaries and expla natio ns con nected

w i t h t h em . T h e s e a n n o t a t i o n s w o u l d h e l p t ]n e w r i t e r o r s c h o l a r k e e p t r a c k o f h is

p r e v i o u s i d e a s, r e a c t i o n s a n d p l a n s , o f t e n c o n f u s i n g l y f o r g o t t e n.

I n a d d i t i o n t o t h e s e s t a t i c f a c i l i t i e s , t h e s y s t e m w o u l d h a v e v a r i o u s p r o -

vision s for change. The user must be able to change both the content s of his file

a n d t h e w a y t h e y a re a r r a n ge d . F a c i l i t i e s w o u l d b e a v a i l a b l e f o r t h e r e v i s i n g a n d

rewo rdin g of text. More over, changes in t]he arran geme nts of the file's compo nent

p a r t s s h o u l d b e p o s s i b l e , i n c l u d i n g c h a n g e s i n s e q u e n ce , l a b e l l i n g , i n d e x i n g a n d

comments.

I t w a s a l s o i n t e n d e d t h a t t h e s y s t e m w o u l d a l l o w i n d e x m a n i p u l a t i o n s w h i c h

we may call dynam ic outlini ng (or dyna mic ~indexing). Dyna mic outli ning uses the

c h a n g e i n o n e t e x t s e q u e n c e t o g u i de a n a u t o m a t i c c h a n g e i n a n o t h e r t e x t s e q u e nc e .

That is, changi ng an outli ne (or an index) changes the sequen ce of the mai n text

w h i c h i s l i n ke d w i t h i t . T h i s w o u l d p e r m i t a w r i t e r t o c r e a t e n e w d r a f t s w i t h a

r e l a t i v e l y s m a l l a m o u n t o f e f f o r t , n o t c o u n t i n g r e w o r d i n g s .

H o w e v e r , b e c a u s e i t i s n e c e s s a r y t o ,e x a mi n e c h a n g e s a n d n e w a r r a n g e m e n t s b e -

fore deciding to use or keep them, the syst em must not commit the user to a new

v e r s i o n u n t i l h e is r e a d y. I n d e e d , t h e s y s t e m w o u l d h a v e t o p r o v i d e s p i n - o f f

f a c i l i t i e s , a l l o w i n g a d r a f t o f a w o r k t o b e p r e s e r v e d w h i l e i t s s u c c e s s o r w a s

c r e a t e d. C o n s e q u e n t l y t h e s y s t e m m u s t b e a b l e t o h o l d s e v e r a l - - i n f a c t, m a n y - -

d i f f e r e n t v e r s i o n s o f th e s a m e s et s o f m a t e r i a l s . M o r e o v e r , t h e s e a l t e r n a t e v e r -

s i o n s w o u l d r e m a i n i n d e x e d t o o n e a n o t h e r , s o t h a t h o w e v e r h e m i g h t h a v e c h a n g e d

t h e i r s e q u e n c e s , t h e u s e r c o u l d c o m p a r e t h e i r e q u i v a l e n t p a r t s .

T h r e e p a r t i c u l a r f e a t u r e s, t h e n, w o u l d b e s p e c i a l l y a d a p t e d t o u s e f u l c h a n g e .

T h e s y s t e m w o u l d b e a b l e t o s u s t a i n c h a n ge r s i n t h e b u l k a n d b l o c k a r r a n g e m e n t s o f

i t s c o n t e n t s . I t w o u l d p e r m i t d y n a m i c o u t l i n i n g . A n d i t w o u l d p e r m i t t he s p i n -

o f f o f m a n y d i f f e r e n t d r af t s , e i t h e r s u c c e s s o rs o r v a r i a n t s, a l l t o r e m a i n w i t h i n

the file for comp aris on or use as long as ~needed. Thes e fea tures we may call

e v o l u t i o n a r y .

The last specificat ion, of course, one that emerg ed f rom all the others, was

that it should not be complicated.

8 8 A C M 2 0 t h N a t i o n a l C o n f e r e n c e ~ 1 9 6 5


6/17

These were the origi nal desiderata. It was not expecte d at first that a sys-

tem for this purpos e would have wider scope of applicati on; these jobs seemed to be

q u i t e e n ou g h . A s w o r k c o n t i n u e d , h o w e v e r , t h e s t r u c t u r e b e g a n t o l o o k m o r e s i m p l e ,

p o w e r f u l a n d g en e r a l , a n d a v a r i e t y o f n e w p o s s i b l e u s e s a p p ea r e d . I t b e c a m e a p -

p a r e n t t h a t t he S y s t e m m i g h t b e s u i t e d t o m a n y u n p l a n n e d a p p l i c a t i o n s i n v o l v i n g

m u l t i p l e c a t e g o r i e s , t e x t s u m ma r i e s o r o t h e r p a r a l l e l d o c u m e n t s , c o m p l e x d a t a

s t r u c t u r e s r e q u i r i n g h u m a n a t t e n t i o n , a n d f i l e s w h o s e r e l a t i o n s w o u l d b e i n c o n -

tinuing change.

N o t e t h a t i n th e d i s c u s s i o n t h a t f o l l o ws w e w i l l p r e t e n d w e c a n s i m p l y s e e

into the machin e, and not worr y for the presen t about how we can actua lly see, un-

d e r s t a n d a n d m a n i p u l a t e t h e s e f il e s. T h e s e a r e p r o b l e m s o f h o u s e k e e p i n g , I / 0 a n d

d i s p l a y , f o r w h i c h m a n y s o l u t i o n s a r e p o s s i b l e .

Elements of the ELF

W h a t w a s r e q u i r e d w e m a y c a l l a n e v o l u t i o n a r y f i l e s t ru c t u r e : a f i l e s t ru c -

ture that can be shaped into various forms, change d fr om one arrange ment to anothe r

in accor dance with the user's cha nging need. It was apparent also that some type

of list struct ure was necessary. Maki ng the file out of lists woul d allow differ -

e n t c a t e g o r i e s o f p e r s o n a l n o t e s , s e p a r a t e d r a f t s , o u t l i n e s a n d m a s t e r i n d i c e s a l l

to be handle d as lists of some sort; their segments could then be mani pula ted

t h r o u g h a u t o m a t i c h a n d l i n g o f i n d e x n u m b e r s. T h e r e s u l t i n g f i l e s t r u c t u r e I w i l l ,

a c c o r d i n g l y , c a l l t h e E v o l u t i o n a r y L i s t F i l e , o r E L F , s i n c e i t i s a n e v o l u t i o n a r y

f i l e s t r u c t u r e c o n s t r u c t e d w i t h l i s t s. T h e s y s t e m p r o p o s e d h e r e i s n o t t h e o n l y

ELF possible. It is built upon a specifi c techniq ue of attac hing lists togethe r

w h i c h h a s a n a t u r a l r e s i s t a n c e t o b e c o m i n g c o n f u s e d a n d m e ss y .

A s c o m p u t e r - b a s e d s y s t e m s g r o w i n c a p a b i l i t y a n d d i v e r s i t y o f u s e s , t h e y t en d

t o b e c o m e m o r e a n d m o r e c l u t t e r e d w i t h n i g g l i n g c o m p l i c a t i o n s , h i d d e n p a s s a g e w a y s ,

a n d l u r k in g , d e t a i l e d i n t e rl o c k s , r e s t r i c t i o n s , s p e c i a l i z a t i o n s , p r o vi s o s . T h e s e

should be forsworn, if possible, in the system under discussion, so that it might

b e a t t r a c t i v e t o l a y m e n ( i n c l u d i n g a r t is t s a n d w r i t e r s ) w h o f e e l u n k i n d l y d i s p o s e d

toward computers. It should readily adapt to their own styles of hand ling things,

imposing few conventi ons or method s of use. How could this impos ition be avoided?

A n d a m o n g s o m a n y i n t e r e s t i n g a n d p o s s i b l e s y s t e m f u n c t i o n s a n d f i l e r e l at i o n s ,

h o w m a y t h e u s e r s k n o w w h a t c o n n e c t i o n s t o m a k e , h o w m a y t h e y u n d e r s t a n d w h a t t h e y

are doing, and how may they avoid muddl ing and losing the things they are work ing

w i t h ?

The answer, I think you see, is to choose a very simple s truct ure that can be

u s e d an d c o m p o u n d e d i n m a n y d i f f e r e n t w a y s . T h e b a s i c a r r a n g e m e n t c h o s e n f o r th e s e

purposes is an infor matio n structure I will refer to as zippere d lists. (We migh t

c a l l it p e r m u t a t i o n - i n v a r i a n t o n e - f o r - o n e i n t e r - l i s t e n t r y - l i n k i n g , b u t t h a t is n o t

n e c e s s a r y . )

There are only three kinds of things in the zippe red-li st ELF, wit h no pre-

d e t e r m i n e d r e l a t i o n s a m o n g t h e m - - n o h i e r a r c h i e s , m a c h i n e - b a s e d f e a t u r es o r t r i c k

e x c e p t i o n s . T h e s y s t e m is u s e r - o r i e n t e d a n d o p e n - f a c e d , a n d i t s c l e a r an d s i mp l e

rules may be adapted to all purposes.

The ELF has three elements: entries, lists and links. An entry is a discr ete

unit of informati on designa ted by the user. It can be a piece of text (long or

short), a string of symbols, a pictur e or a control des igna tion for physi cal ob-

jects or operatio ns.



7/17

A l i s t is a n o r d e r e d s e t o f e n t r i e s d e s i g n a t e d b y t he u s e r . A g i v e n e n t r y

m a y b e i n a n y n u m b e r o f l i s t s .

A l i n k i s a c o n n e c t o r , d e s i g n a t e d b y t h e u s e r , b e t w e e n t w o p a r t i c u l a r e n -

t r i e s w h i c h a r e i n d i f f e r e n t l i st s ; F i g u r e I. A n e n t r y i n o n e l i s t m a y b e l i n k e d

t o o n l y o n e e n t r y i n a n o t h e r l i s t .

O n t h e l e f t w e s e e t w o z i p p e r e d l i s t s . B e t w e e n t h e e n t r i e s o f l i s t A a n d

t h o s e o f B a r e d a s h e d l i n e s , r e p r e s e n t i n g t h e l i nk s b e t w e e n t h e tw o l i s t s . O n t h e

r i g h t i s t h e t a b l e o f l i n k s a s i t m i g h t l o o k t o a m a c h i n e . T h e m a c h i n e c a n r e a d

t h i s t a b l e f r o m r i g h t t o l e f t o r l e f t t o r i g h t , f i n d i n g e n t r i e s i n B t h a t c o r r e -

s p o n d t o g i v e n e n t r i e s i n A , o r v i c e v e r sa . A c h a n g e i n t he s e q u e n c e o f e i t h e r

l i s t , o r a d d i t i o n s t o e i t h e r l i s t , w i l l n o t : c h a n g e t h e l i n k s t h a t s t a n d b e t w e e n

t h e m. C h a n g e s i n t he l i n k s t r u c t u r e w i l l o c c u r o n l y i f t h e u s e r s p e c i f i c a l l y

c h a n g e s t h e l in k s , o r i f h e d e s t r o y s e n t r i e s w h i c h a r e l i n k e d t o o t h e r s .

T o b e t e c h n i c a l , t h e n , t w o l i s t s a r e z i p p e r e d i f t h e r e a r e a n y p a i r w i s e l i n k s

b e t w e e n t h e i r r e s p e c t i v e e l e m e n t s , e a c h e l e m e n t i s i n n o m o r e t h a n o n e l i n k p ai r ,

a n d t h e s e l i n k s a r e u n a f f e c t e d b y p e r m u t a t i o n o f t he l i s ts , r e m a i n i n g a f f i x e d t o

t h e s a m e p a i r s o f e l e m e n t s . I t is n o t r e q u i r e d t h a t t h e t w o l i s t s b e o f t h e s a m e

l e n g t h , o r , e v e n i f t h e y a r e , t h a t a l l e n t r i e s h a v e a l i n k t o t h e o t h e r l i s t .

T h e E L F ' s F i l e O p e r a t i o n s

Z i p p e r e d l i s t s a r e a n i n f o r m a t i o n s t r u c t u r e ; t h e E v o l u t i o n a r y L i s t F i l e i s a

f i l e s t r u c t u r e . T h e E L F d e s c r i b e d i n t h i s p a p e r h o l d s i ts c o n t e n t s e x c l u s i v e l y a s

z i p p e r e d ( o r u n z i p p e r e d ) l i s ts . B u t th e f i l e s t r u c t u r e m u s t a l s o i n c l u d e a s e t o f

o p e r a t i o n s b y w h i c h i t m a y b e m o d i f i e d . T h e s e f i l e o p e r a t i o n s e x i s t f o r c r e a t i n g ,

a d j u s t i n g o r r e m o v i n g t h e e n t r y , l i s t a nd ] Li nk , a n d f o r m a n i p u l a t i n g t h e s e q u e n c e

r e l a t i o n . A n E L F i s a c t u a l l y a n y m a c h i n e ~ i c h w i l l , o n c o m m a n d , c a r r y ou t t he

b a s i c o p e r a t i o n s o n e n t r y , l i s t, l i n k an d s e q u e n c e.

E n t r i e s. T h e u s e r m a y c r e a t e n e w e n t r i e s a t a n y t im e , p u t t i n g a n y t h i n g i n

t h e m t h a t h e t h i n k s a p p r o p r i a t e . E n t r i e s ~ y b e c o m b i n e d o r d i v i d e d ( u n l e s s i n -

d i v i s i b l e , l i k e o b j e c t s , c o m m a n d s , e t c . ) E n t r i e s m a y b e p u t i n a n y l i s t, a nd t h e

s a m e e n t r y m a y b e p u t i n d i f f e r e n t l i s ts . T h e u s e r m a y d i r e c t t h a t e n t r i e s o f o n e

l i s t b e a u t o m a t i c a l l y c o p i e d o n t o a n o t h e r l i s t , w i t h o u t a f f e c t i n g t h e o r i g i n a l

list.

L i s t s . T h e u s e r m a y c r e a t e l i s t s a n d a s s i g n e n t r i e s t o th e m . H e m a y a t w i l l

m a k e n e w c o pi e s o f l i s ts . H e m a y r e a r r a n g e t h e s e q u e n c e o f a l i s t, o r c o p y t he

l i s t a n d c h a n g e t h e s e q u e n c e o f t h a t c op y . L i s t s m a y b e c o m b i n e d ; l i s t s m a y b e c u t

i n t o s u b l i s t s .

L i n k s . T h s u s e r m a y c r e a t e l i n k s b e t w e e n e n t r i e s t h a t a r e i n d i f f e r e n t

l i st s . A n y n u m b e r o f l e g al l i n k s m a y b e c r e a t e d , a l t h o u g h t h e u p p e r l i m i t o f

l i n k s b e t w e e n a n y t w o l i s ts i s d e t e r m i n e d b y t he l - f o r - I r u l e. W h e n a n e n t r y o r a

l i s t i s c o p i e d i n t o a l is t , l i n k s w i l l r e m a i n b e t w e e n p a r e n t a n d d a u g h t e r e n t r i e s.

M o r e o v e r , a f t e r a l i s t - c o p y i n g o p e r a t i o n , t h e d a u g h t e r l i s t w i l l h a v e t h e s a m e

l i n k s t o a l l o t h e r l i s t s a s d o e s t h e p a r e n t l i s t .

S e q u e n c e s . T h e u s e r m a y p ut a l i s t i n a n y s e q u e n c e h e w i s h e s . ( A c o p i e d

l i s t w i l l m a i n t a i n t h e o r i g i n a l s e q u e n c e u n t i l m o d i f i e d . ) S e q u e n c e s m a y b e t r a n s -

f e r r e d b e t w e e n l i s t s v i a t h e l in k s : i f t h e s e q u e n c e o f A i s t r a n s f e r r e d t o B , e a c h

e n t r y o f A l i n k e d t o a n e n t r y i n B t a k e s t il e s e q u e n t i a l p o s i t i o n o f i t s l i n k e d



8/17

entry in B.

No definite mean ing is assign ed to these entities or operatio ns by the sys-

tem; the user is free to let them mea n anythi ng he likes. A list may be a cate-

gory, trail, index, dialogue , ca talogu e or poem, and lists may be assem bled into

larger structures. The ELF may be thought of as a place; not a machi ne, but a

p i e c e o f s t a t i o n e r y o r o f f i c e e q u i p m e n t w i t h m a n y l i t t l e l o c a t i o n s w h i c h m a y b e

r e a r r a n g e d w i t h r e g a r d t o on e a n o t h e r * * * * .

N o t e t h a t z i pp e r e d l i s ts g e n e r a t e o n l y o n e o f v a r i o u s p o s s i b l e E v o l u t i o n a r y

List Files. Indeed, the desc ript ion of the file structu re given here is in some

ways res trictive: the ELF could take a number of other, clos ely simil ar forms and

still be much the same thing. For example, it woul d be possi ble to allo w sub-

entries and sup erentri es into the file, to behave and link up like norma l entries,

e v e n t h o u g h t h ey c o n t a i n e d o r w e r e c o n t a i n e d i n o th e r e n t r i e s. B u t t he e q u i v a l e n t

c a n b e do n e w i t h t h e c u r r e n t s y s t e m. A n o t h e r p o s s i b i l i t y w o u l d b e t o a l l o w l i n k s

other than 1-for-l; these could be modal, the diffe rent link-modes havin g differ-

ent meanin gs to the user. Or we might make it an evol utio nary netw ork file, allow-

ing any two entries to be connected. Or, besides s uch general changes in the

r u l e s , p l a u s i b l e c h a n g e s a n d a c c e s s o r y f u n c t i o n s f o r a n y p u rp o s e s c o u l d b e i n t ro -

d u c e d o u t s i d e t h e g i v e n f i l e s tr u c t u r e , e v e n i n c l u d i n g m o d i f i c a t i o n s a n d w i d g e t s

to do some of the same things more easily.

B u t t o t h e u s e r s u c h c o m p l i c a t i o n m i g h t r e n d e r t h e s y s t e m f a r l e ss h a n d y o r

perspicu ous. The ELF, wit h its assoc iated techn iques as descr ibed above, is

s i m p l e a n d u n i f i e d . M a n y t a s k s c a n b e h a n d l e d w i t h i n t h e f i l e s t r u c t u r e . T h i s

m e a n s i t c a n b e o f p a r t i c u l a r b e n e f i t t o p e o p l e w h o w a n t t o l e a r n w i t h o u t c o m p l i -

c a t i o n s a n d u s e i t i n w a y s t h e y u n d e r s t a n d . F o r p s y c h o l o g i c a l , r a t h e r t h a n te c h -

nical reasons, the syste m should be lucid and simple. I belie ve that this ELF

b e s t m e e ts t h e s e r e q u i r e m e n t s .

T e c h n i c ~ l A s p e c t s

Since the ELF desc ript ion above bears some resembl ance to the list languages,

such as IPL, SLIP, etc., a dist inct ion shou ld be drawn. These list languages ~ are

p a r t i c u l a r l y s u i t e d t o p r o c e s s i n g d a t a , f a s t a n d i t e r a t i v e l y , w h o s e e l e m e n t s a r e

m a n i p u l a b l e i n N e w e l l - S h a w - S i m o n l i s t s. E s s e n t i a l l y t h e y m y b e t h o u g h t o f a s o r -

g a n i z a t i o n s o f m e m o r y w h i c h f a c i l i t a t e s e q u e n t i a l o p e r a t i o n s o n u n p r e d i c t a b l y

b r a n c h i n g o r h i e r a r c h i c a l d a t a . T h e s e d a t a m a y c h a n g e f a r t o o q u i c k l y f o r h u m a n

i n t e r v e n t i on . E v o l u t i o n a r y f i l e s t r u c t u r e s , a n d t he E L F i n p a r t i c u l a r , a r e d e-

s i g n e d t o b e c ha n g e d p i e c e m e a l b y a h u m a n i n d i v i d u a l . W h i l e i t m i g h t b e c o n v e n i e n t

to pro gram an ELF in one of these languages , the low speed at whic h user file com-

m a n d s n e e d t o b e e x e c u t e d m a k e s s u c h h i g h - p o w e r e d i m p l e m e n t a t i o n u n n e c e s s a r y ; t h e

m a i n p r o b l e m i s t o k e e p t r a c k o f t h e f i l e 's a r r a n g e m e n t s , n o t t o p e r f o r m c o m p u t a -

t i o n o n i t s c o n t e n t s. A l t h o u g h w o r k h a s b e e n d o n e t o a c c o m o d a t e t h e l i s t - l a n g u a g e

appr oach to larger chunks o f mate rial than usual I0, the things people will w ant to

put into an ELF will typica lly be too big for core memory.

The ELF does in fact share some of the problems of the list languages: not

a v a i l a b l e - s t o r a g e a c c o u n t i n g o r g a r b a g e c o l l e c t i o n ( c o n c e rn s a s s o c i a t e d w i t h o r -

g a n i z a t i o n o f f a s t m e m o r y f o r p r o c e s s i n g , w h i c h m a y b e a v o i d e d a t s l o w e r s p e e d s ) ,

but the probl ems of checkout for dispo sal (what other lists is an entry on?) and

list naming. The former prob lem is rather strai ghtf orwa rdly solve d II, P 164; the

latter is complicated in ways we cannot cover here.



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T h e E L F a p p e a r s t o be c l o s e s t , t o p o l o g i c a l l y a n d i n o t h e r o r g a n i z i n g f e a -

tures, to the Mult ilis t s ystem descri bed by Prywes and Gray 12. Like that system,

i t p e r m i t s p u t t i n g e n t r i e s i n m a n y d i f f e r e n t l i s ts a t o n c e. H o w e v e r , i n c u r r e n t

intent 13 that syst em is firmly hierarch ical, and thus som ewhat removed from the

E L F ' s s c o p e o f a p p l i c a t i o n . A n o t h e r c l o s e l y r e l a t e d s y s t e m i s t h e I n t e g r a t e d D a t a

S t o r e o f B a c h m a n l 4 , 1 5 , 1 6 , 1 7 , 1 8 ; t h i s i s i n t e n d e d a s a h a r d w a r e - s o f t w a r e s y s t e m f o r

disc I/0 and storage arrange ment, but in its details it seems the ELF's close

r e l a t i v e. E a c h o f t he s e s y s t e m s h a s a c o r m e c t i o n l o g i c t ha t m i g h t b e f e a s i b l e a s

a basis for an ELF diffe rent from this one. Or, eithe r migh t prove a conve nien t

p r o g r a m m i n g b a s e f o r t he i m p l e m e n t a t i o n o f t h i s f i l e st r u c t u r e .

A n o t h e r o b v i o u s t e c h n i c a l q u e s t i o n = m s t b e c o n s i d e r e d . H o w c a n t he E L F al -

l o w u n l i m i t e d c o p i e s o f e n t r i e s a n d l i s t s ? B y p a t c h i n g t e c h n i q u e s , o f c o u r s e.

V a r i a n t e n t r i e s a n d l i s t s c a n t a ke v i r t u a l l y n o s p a c e , b e i n g m o d i f i c a t i o n d a t a

p l u s p o i n t e r s t o t he o ri g i n a l . W h e n a m o d i f i e d v e r s i o n o f a li s t o r e n t r y i s

c r e a t e d , t h e m a c h i n e p a t c h e s t h e o r i g i n a l w i t h t h e c ha n g e s n e c e s s a r y t o m a k e t h e

m o d i f i e d v e r s i o n : F i g u r e 2 .

U S E S

I n t h e d i s c u s s i o n t h a t f o l l o w s , w e w i l l e x a m i n e v a r i o u s p o s s i b l e a p p l i c a t i o n s

o f z i p p e r e d l i s t s a n d t h e E L F , a n d p o s t p o n e d i s c u s s i n g t h e f i l e l a n g u a g e t h e y r e -

q u i re . F i n a l l y w e w i l l r e t u r n t o t hi s p r o b l e m , a n d d e s c r i b e t h e f il e l a n g u a g e

P R I D E w h o s e a d d i t i o n a l f e a t u r e s a r e n e e d e d t o a d a p t t h e E L F f o r t h e u s e s o r i g i n a l l y

d i s c u s s e d .

By assig ning entries to lists, the ELF may be used as a glor ifie d card file,

w i t h s e p a r a t e l i s t s u s e d f o r c a t e g o r i e s , t r a i ls , e t c. T h i s p e r m i t s e x t e n s i v e

c r o s s - i n d e x i n g b y t h e a s s i g n m e n t o f on e e n t r y to d i f f e r e n t l i st s . I t p e r m i t s s u b -

s e t s a n d s u b - s e q u e n c e s f o r a n y u s e t o b e h e l d a p a r t a n d e x a m i n e d w i t h o u t d i s t u r b i n g

t h e l i s t s f r o m w h i c h t h e y h a v e b e e n d r a w n , b y c o p y i n g t h e m o n t o o t h er , n e w l i s t s .

T h e E L F p e r m i t s t h e f i l i ng o f h i s t o r i c a l t r a i l s o r a s s o c i a t i v e ( B u sh ) t r a i l s

t h r o u g h do c u m e n t s , b u s i n e s s c o r r e s p o n d e n c e , b e l l e s - l e t t r e s , c a s e l aw , t r e a ti e s ,

s c h o l a r l y f i e l d s a n d h i s t o r y , a n d t h e m i x t u r e o f t r a i l w i t h c a t e g o r i c a l f i l in g .

T h e s e a r e t he s i m p l e u s e R ; t h e c o m p o u n d u s e s ar e m u c h m o r e i n t e r e s t i n g . B u t

s i n c e w e c a n n o t i n t u i t i v e l y f i t e v e r y p o s s i b l e c o n c e p t u a l r e l a t i o n s h i p i n t o z ip -

p e r e d l i s t s , i m a g i n a t i v e u s e is n e c e s s a r y . R e m e m b e r t h a t t h er e is n o c o r r ec t w a y

t o u s e t h e s y s t e m. G i v e n i t s s t r u c t u r e , t h e u s e r m a y f i g u r e o u t a n y m e t h o d u s e f u l

t o h i m . A n u m b e r o f d i f f e r e n t a r r a n g e m e n t s c a n b e c o n s t r u c t e d i n t h e E L F , u s i n g

o n l y t h e b a s i c e l e m e n t s o f e nt r y , l i s t a nd l i n k. Z i p p e r e d l i s ts m a y b e a s s e m b l e d

i n t o r e c t a n g u l a r a r r a y s , l a t t i ce s a n d m o r e i n t r i c a t e c o n f i g u r a t i o n s . T h e s e as -

s e m b l i e s o f l i s ts m a y b e a s s i g n e d m e a n i n g i n c o m b i n a t i o n b y t h e u s e r , a n d t h e s ys -

t e m w i l l p e r m i t t h e m t o b e s t o r e d , d i s p l a y e d , t a k e n a p a r t f o r e x a m i n a t i o n , a n d c o r -

r e c t e d , u p d a t e d , o r m o d i f i e d .

B y u s i n g s u c h c o m b i n i n g a r r a n g e m e n t s o n l i s t s c o m p o s e d o f t e x t , t h e f i l e c a n

b e s e l f - d o c u m e n t i n g , w i t h a l l l a b e l l i n g a nd d o c u m e n t a t i o n k e p t i n t e g r a l l y w i t h i n

the file structure. It is thus poss ible to incorporate, in a body of info rmat ion

f i l e d i n t he EL F , v a r i o u s l e v e ls o f i n d e x , s u n m m r y , e x p l a n a t i o n a n d c o m m e n t a r y .

M a n y u s e f u l w a y s o f l i s t i n g a n d l i n k i ng s u c h d o c u m e n t a t i o n a r e p o s s i bl e . I n F i g u r e

3 we see some of the ways that docu ment ary lists may be linked together. The lists

s h o w n a re o u t l i ne , s u b o u t l i n e , d r a f t , s u b d r a f t , s u m m a r y , c o m m e n t a r y a n d s o u r c e

list. These are not all the possi ble types of docu ment ary lists; for example,

f o o t n o t e s a r e o m i t t e d . T h e E L F w i l l p e r m i t a n y n u m b e r o f t h e s e d o c u m e n t a r y l i s t s;



10/17

f o r e x a m p l e , f o o t n o t e s a r e o m i tt e d . T h e E L F w i l l p e r m i t a n y n u m b e r of t h e s e

d o c u m e n t a r y l i s ts ; o b s e r v e t h a t t h e y c a n b e b u i l t o n o n e a n o t h e r , a n d i n d e f i n i t e l y

c o m p ou n d e d. T h e s y s t e m w i l l h a v e n o t r o u b l e a c c e p t i n g a c o m m e n t a r y o n a c o m m e n t a r y

o n a s u b d r a f t o f a n o u t l i n e f o r a v a r i a n t l i s t o f s o u r c e m a t e r i a l s .

F i g u r e 3 s h o w s a l s o h o w t w o l is t s m a y c o n t a i n s o m e o f t h e s a m e e n t r i e s . T h e

d a s h e d l i n e r e p r e s e n t s l i n k a g e b e t w e e n e n t r i e s , t h e s o l i d l i n e s h o w s t h a t b o t h

l i s t s c o n t a i n t h e s a m e e n t r y. T h i s m a y b e u s e f u l f o r c r e a t i n g a l t e r n a t e v e r s i o n s ,

o r , as i n t h i s e x a m p l e , t h e l i s t s c o n t a i n i n g t h e s a m e e n t r y m a y h a v e d i f f e r e n t p u r -

p o s e s . H e r e , f o r i n s t a n c e , a n e n t r y i n t he s u m m a r y i s a l s o t o b e f o u n d i n t h e m a i n

d r a f t .

T h i s s e l f - d o c u m e n t a t i o n f e a t u r e p e r m i t s a n y s t r i n g o f t e xt i n th e E L F, l o n g

o r s h o r t, t o b e a n n o t a t e d o r f o o t no t e d f o r s c h o l a r l y o r o t h e r p u r p o s e s . S u c h m a r -

g i n a l i a c a n b e t e m p o r a r y o r p e r m a n e n t , f o r th e p r i v a t e m e m o r a n d a o f a n i n d i v i d u a l

o r f or c o m m u n i c a t i o n a m o n g d i f f e r e n t p e r s o n s u s i n g t h e f il e .

I n a l i ke m a n n e r , t h e E L F i s c a p a b l e o f s t o r i n g m a n y t e x t s i n p a r a l l e l , i f

t h e y a r e e q u i v a l e n t o r l i n k e d i n s o m e w a y . F o r e x a m p l e , i n s t r u c t i o n m a n u a l s f o r

d i f f e r e n t m o d e l s o ~ t h e s a m e m a c h i n e m a y b e k e p t i n t h e f i l e a s l i n k e d l i s t s , a n d

r e f e r r e d t o w h e n m a c h i n e s a r e t o b e c o m p a r e d , u s e d o r f i xe d . T h i s i s o f s p e c i a l

u s e t o r e p a i r m e n , p r o j e c t m a n a g e r s a n d t e c h n i c a l w r i t e r s .

M o r e o v e r , t h e E L F ' s c r o s s - s e q u e n c i n g f e a t u r e - - t h e f a c t t h a t l i n k s i g n o r e

p e r m u t a t i o n s - - p e r m i t s t h e c o l l a t i o n o f v e r y d i f f e r e n t c o g n a t e t e x t u a l m a t e r i a l s

f o r c o m p a r i s o n a n d u n d e r s t a n d i n g . I n l a w, t h is w o u l d h e l p i n c o m p a r i n g s t a t u t e s

( o r w h o l e l e g a l s y s t e ms ) ; i n l i t e r a t u r e , v a r i o r u m e d i t i o n s a n d p a r o d i e s . T h u s s u c h

b o d i e s a s t he I n t e r p r e t e r ' s B i b l e a n d a T o t a l S h a k e s p e a r e ( i n c o r p o r a t i n g F o l i o s ,

b o w d l e r i z a t i o n s , s a t i r e s a n d a l l c r i t i c a l c o m m e n t a r y ) c o u l d be a s s e m b l e d f o r s t ud y .

L e t m e t r y t o i l l u s t r a t e t h e p o s s i b l e c o m p r e h e n s i v e n e s s a n d v e r s a t i l i t y o f

t h i s f i l e s t r u c t u r e a s a p p l i e d t o t e x t s . F i g u r e 4 s h o w s t h e d i f f e r e n t a r r a n g e m e n t s

t h a t m i g h t b e us e d b y o n e m a n - - i n t h is c a s e a n h i s t o r i a n w r i t i n g a b o o k - - t o a s -

s e m b l e a n d i n t e g r a t e h i s i n t e l l e c t u a l a n d p r o f e s s i o n a l c o n c e r n s . A l t h o u g h i t i s

i m p o s s i b l e t o s h o w t h e l i nk s b e t w e e n a l l t h e s e p a r a t e e n t r i e s o f t h e s e l i s t s - - t h e

e n t r i e s a r e n o t t h e m s e l v e s d i s c e r n i b l e i n t h i s d r a w i n g - - i t i s p o s s i b l e t o n o t e t h e

k i n d s o f l i n k s b e t w e e n l i s t s . A t h i n l i n e b e t w e e n l i s t s s h o w s t h a t s o m e li n k s

e x i s t ; a s o l i d l i n e i n d i c a t e s t h a t s o m e e n t r i e s o f b o t h l i s t s a r e t h e sa m e .

P e r h a p s t h i s l oo k s c o m p l i c a t e d . I n f a c t , e a c h o f t h e c o n n e c t o r s s h o w s a n i n -

d e x i n g o f o n e b o d y o f i n f o r m a t i o n t o a n o t h e r ; t h i s u s e r m a y q u e r y h i s f i l e i n a n y

d i r e c t i o n a l o n g t h e s e l i n k s , a n d l o o k u p t h e p a r t s o f o n e l i s t w h i c h a r e r e l a t e d t o

p a r t s o f a n o t h e r. T h e r e f o r e t h e l i n es m e a n k n o w l e d g e a n d or d e r . N o t e t h a t i n s u c h

u s e s i t i s t h e m a n ' s j o b t o d r a w t h e c o n n e c t i o n s , n o t t h e m a c h i n e ' s . T h e m a c h i n e

i s a r e p o s i t o r y a n d n o t a ju d g e .

T h e E L F m a y b e a n a i d t o t h e m i n d i n c r e a t i v e t a s k s , a l l o w i n g t h e u s e r t o c o m -

p a r e a r r a n g e m e n ts a n d a l t e r n a t i v e s w i t h s o me p r i o r i d ea l . T h i s is h e l p f u l i n

p l a n n i n g n o n l i n e a r a s s e m b l a g e s ( m u s e u m e xh i b i t s , c a s t i n g f o r a p l a y, ) o r l i n ea r c o n -

s t r u c t i o n s o f a n y k i n d. S u c h l i n e a r c o n s t r u c t i o n s i n c l u d e n o t o n l y w r i t t e n t e x ts ;

t h e y c a n b e a n y c o m p l i c a t e d s e q u e n c e s o f t h i n g s , s u c h a s m o t i o n p i c t u r e s ( i n t h e

e d i t i n g s t a g e ) a n d c o m p u t e r p r o g r a m s .

I n d e e d , c o m p u t e r p r o g r a m m i n g w i t h a n o n - li n e d i s p l a y a n d t h e E L F w o u l d h a v e

a n u m b e r o f a d v a n t a g e s . I n s t r u c t i o n s m i g h t b e i n t e r l e a v e d i n d e f i n i t e l y w i t h o u t



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resorting to tiny writing. Moreover, the programmer could keep up work on several

variant approaches and versions at the sane time, and easily document their over-

all features, their relations to one another and their correspond ing parts. Add-

ing a load-and-go co mpiler would create a self-do cumenti ng pr ogramming scratchpad.

The natural shape of information, too, may call for the ELF. For instance,

sections of information o ften arrange themselves natura lly in a lattice structure,

whose strands .need to be separately examined, pondered or tested. Such lattices

include PERT networks, programmed instructi on sequences, his tory books and genealog-

ical records. (The ELF can handle geneal ogical source documentat ion and its orig-

inal text as well.) Indeed, any informatio nal networks that require storage, han-

dling and consid eration w ill fit the ELF; a feature that could have applica tions

in plant layout, social psychology, conting ency planning, circuit design and itin-

eraries.

The ELF may, t hrough its mutability:, its expa nsib ilit y, and its self -doc umen -

tation features, aid in the integration, underst anding and channeling of ideas and

problems that will not yield to ordin ary analysis or customary reductions; for in-

stance, the contingencies of planning, which are only partia lly Boolean. Often the

reason for a so-called Grand Str ategy in a setting is that we cannot keep track of

the interrelatio ns of particul ar contingencies. The ELF could help us understand

the interrelatio ns of possibili ties, consequences, and strategi c options. In a

logically similar case, evaluating espionage, it might help trace consistenci es and

contradiction s among reports from different spies.

The use of an ELF as the basis for a manag ement informati on system is not in-

c o n c e i va b l e . I t s e v o l u t i o n a r y c a p a b i l i t y w o u l d p r o v i d e a s m o o t h t r a n s i ti o n f r o m

the prior systems, phasi ng out old paper work forms and information channels piec e-

meal. Beginnin g with conventional acco unting arrays and informati on flow, and mov-

ing through discrete ev olution ary steps, the ELF might help restructu re an entire

corporate system. Numeric al subro utining could permit the syste m to encompass all

bookkeeping. The addresses of all transact ion papers, zippered to lists of their

dates and contents, would aid in control ling shipments, invento ry and cash. The

ELF's cross- sequenci ng feature could be put to concrete uses, helpin g to rearrang e

warehou ses (and the company library) by direct ing the printout of new labels to

guide physical rearrangement. Inventories, proper ty numbers and patents could be

so catalogued and recatalog ued in the ELF. Lega l documents, corr espondence, com-

pany facts and history could be indexed oi: filed in histor ical and categor y trails.

And upper managem ent could add private ann otations to the public statements, re-

ports and research of both the organ izatio n and its competitors, wi th amendments,

qualifications , and inside dope.

P R I D E

While the ELF as describ ed is expected to be general and useful, the origin al

purposes describe d at the beginni ng of this paper call for certain further pro-

visions. Now I would like to describe a desirab le file and inform ation handl ing

language that will meet these needs, called the PRIDE (Personalized Retrieval, In-

dexing, and Docum entat ion Evolutionary ) System. Its purpos e is to facilitate the

use of an ELF. The system described is not yet implemented, nor even fully speci-

fied, but let us speak as t hough it is.

PRIDE includes the ELF operations. However, for safety and convenienc e near-

ly every operatio n has an inverse. The u~er must be permitted, given a list of

wha t he has done recent ly, to undo it. It: follows that destro y inst ruct ions must



12/17

fail safe; if given accid ental ly, they are to be revocable . For safety's sake, it

s h o u l d t a k e s e v e r a l s t e p s t o t h r o w a t h in g a w a y c o m p l e t e l y . A n i m p o r t a n t o p t i o n

w o u l d p e r m i t t h e u s e r t o r e t r a c e c h r o n o l o g i c a l l y e v e r y t h i n g h e d o e s o n t h e s ys t e m .

M o s t o f P R I D E ' s a p p l i c a t i o n s w i l l i n v o l v e t e x t h a n d l i n g , e i t h e r a s a p r i m a r y

p u r p o s e o r i n t he d o c u m e n t a t i o n o f s o m e o t h e r t a s k. H e n c e a n u m b e r o f f e a t u r e s

e x i s t f o r c o n v e n i e n t t e x t u s a g e . T e x t h a n d l i n g c o n ~ a n d s ( f o r m o d i f y i n g e n t r i e s)

i n c l u d e t h e e q u i v a l e n t s o f s t a n d a r d p r o o f r e a d e r ' s m a r k s f o r i ns e r t i o n , d e l e t i o n a n d

switching of sections.

A l s o f o r t e x t u s a g e a n d u s e r c o m f o r t , t h e r e a r e c e r t a i n s y s t e m n o n - r e s t r i c -

tions. There is no practi cal res tric tion on the length of an input entry, and it

n e e d f o l l o w o n l y t h e m o s t t r i v i a l f o r m a t c o n v e n t i o n s . I n a d d i t i o n , t h e m a c h i n e

w i l l i n t e r r u p t a n y o t h e r P R I D E f u n c t i o n t o r e c e i v e i n p u t t e x t ( i n s p i r a t i o n m o d e ) .

I t i s n e c e s s a r y t h a t e nt r i e s o f u n s p e c i f i e d l e n g t h b e a c c e p t a b l e t o th e s y s t e m

with out fuss or warning . PRIDE does not stipul ate fixed record lengths, either for

i n p u t or s t o ra g e ; a n y s u c h r e s t r i c t i o n s w o u l d h a v e a p s y c h o l o g i c a l l y c r a m p i n g e f -

fect. There is no reason the system cannot appe ar to the user to have no fixed or

s t a n d a r d u n i t l e n g t h s ; t h e m a c h i n e ' s o p e r a t i n g u n i t s a n d s e c t i o n s s h o u l d n o t c o n -

cern him.

I d e a l l y , n e i t h e r t h e l e n g t h o f e nt r i e s , t h e n u m b e r o f l i s ts , o r a n y o t h e r

p a r a m e t e r o f a f i le i s r e s t r i c t e d b y a n y t h i n g b u t t h e a b s o l u t e s i z e o f a l l m e m o r y .

T h i s is a d i f f i c u l t r e q u i r e m e n t f o r t h e p r o g r a ~ n e r . R o u t i n e l y , h o w e v e r , t h e s y s t e m

should be able to accept entries thousands of charac ters long, accept hundr eds of

entries to a list, and accept hundreds of lists in the file. Otherwise, extran eous

c o n s i d e r a t i o n b y t h e u s e r o f w h e t h e r t h e r e 's r o o m t o a d d m a t e r i a l o r t r y o ut a n o f f -

shoot begins to inte rfere with the system's use.

A l t h o u g h I h a v e a v o i d e d d i s c u s s i n g t h e m e a n s b y w h i c h t h e u s e r s e e s h i s f i le ,

PRIDE must, of course, hav e functions and con~nands for .this purpose. For a CRT

t h e s e i n c l u d e q u i c k l o o k u p s c h e m e s 1 9, p r e f e r a b l y w i t h m o v i n g m e n u s a n d m e a n s o f

r e a d i l y c h a n g i n g t h e h i e r a r c h y o f l o o k u p s t r u c t u r e ; a s w e l l a s v i s u a l c u i n g a n d

m n e m o n i c f o r m a ts , i n c l u d i n g c u r s o r m a n e u v e r s , o v e r l a y s a n d a n i m a t e d w i p e s a n d o t h e r

t r a n s i t io n s . B u t s u c h g l a m o r o u s f e a t u r e s d o n o t r e d u c e t h e c h a l l e n g e o r w o r t h o f

w o r k i n g t h r o u g h a l i ne p r i n t e r , o r s e e k i n g t o m a k e t h e s y s t e m u s e f u l u n d e r a b a t c h-

p r o c e s s i n g m o n i t o r .

M a n y i n s t r u c t i o n s a s i d e f r o m t h o s e a l r e a d y m e n t i o n e d w i l l b e n e e d e d b y t h e

u s e r; p a r t i c u l a r a p p l i c a t i o n s w i l l r e q u i r e s u c h o p e r a t i o n s a s t e x t l o o k u p a n d i n-

t e g e r a r i t h m e t i c . A n d s u r e l y a l l t h e u s e s o f t h e s y s t e m h a v e n o t b e e n a n t i c i p a t e d .

H e n c e a s u b r o u t i n i n g f a c i l i t y i s t o b e a v a i l a b l e, r e a c h i n g t o a s s e m b l y l a n g u a g e o r

o p e n i n g i n t o t he m a c h i n e ' s o t h e r l a n g u a g e s . T h i s c o u l d b e u s e d f o r p r o c e s s i n g t h e

file's contents (e.g., numbers or charact er strings), or for creating more conven-

i e n t c o m b i n e d o p e r a t i o n s o u t o f t h e d i f f e r e n t o p e r a t i o n s d e a l i n g w i t h f i l e s t r u c -

ture, input-output and text.

P R I D E i s o n e p o s s i b l e w a y t o m a k e a n E L F , o r a n y e v o l u t i o n a r y f i l e s t r u c t u r e ,

u s e f u l . P R I D E w o u l d b e a f o r eg r o u n d , f r e e - s t a n d i n g l a n g u a g e w i t h t h e p r i m a r y m i s-

s i o n o f h a n d l i n g f i l es a n d m a n u s c r i p t s , a s d i s c u s s e d a t t h e b e g i n n in g , a n d s e c o n d a r y

a p p l i c a t i o n s i n o r d e r i n g a n d d o c u m e n t i n g o t h e r k i n d s o f c o m p l e x i n f o r m a ti o n . I t s

m a j o r u s e w o u l d p r e s u m a b l y b e i n c o n n e c t i o n w i t h t i m e - s h a r e d d i s p l a y a n d i n f o r m a -

tion systems. But such a language is only one suggesti on. Actual ly, the re is not

much re ason that the ELF could not be made a standard file structure for all pur-

p o s e s ; u n u s e d c a p a b i l i t i e s w o u l d n o t i n t r u d e , b u t w o u l d s t i l l b e t h e r e i f u n e x -



13/17

pectedly wanted. ELF systems could

be

built into the file capabilities of general

utility software. The actual computation involved is relatively trivial, and the

ELF could easily be incorporated into I/O routines or data channel languages.

Even small-scale hardw are im plementations are not unthinkable; a control box be-

tween a typewriter and a tape recorder, for instance.

All these applications depend, of ccmrse, on the system being actuall y use-

ful, which is an empirical question. A nt~ber of possible applica tions have been

mentioned. But, except as a crutch to man's fallible mind, is there any reaso n to

suppose that the system has any general appl icabili ty in principle?

P h i l o s o p h y

As philosoph y' I want to speak of two major things. First, comple x file

structures (like the ELF) make possible the creatio n of comple x and significa nt n ew

mediam, the hypert ext and hyperfilm. Second, evolution ary file structures (like

the ELF) make it possib le to keep tr ack of things that have been ch anging, wi thout

our awareness, all along. These include the major c ategories of hu, n thought,

w h i c h w i l l g o o n c h a ng i n g .

Systems o f paper have grave limitations for either organiz ing or presen ting

ideas. A book is never perfec tly su ited to the reader; one reader is bored, an-

other confused by the same pages. No system of paper-- boo k or programm ed text--

can adapt very far to the interests or needs of a particula r reader or student.

H o w e v e r , w i t h t he c o m p u t e r - d r i v e n d i s p l a y a n d m a s s m e m o r y , i t h a s b e c o m e p o s-

sible to create a new, readable medium, for educa tion and enjoyment, that will let

the reader find his level, suit his taste s and find the parts that take on sp ecial

mean ing for him, as instruction or entertainment.

L e t m e i nt r o d u c e t h e w o r d h y p e r t e x t * * * ~ t o m e a n a b o d y of w r i t t e n o r pi c -

t o r i a l m a t e r i a l i n t e r c o n n e c t e d i n s u c h a c o m p l e x w a y t h a t i t c o u ld n o t c o n v e n i e n t l y

be present ed or represen ted on paper. It may contai n sunmmries, or maps of its

contents and their interrelations; it may contain annotations, additions and foot-

notes fr om scholars who have examined it. Let me suggest that such an object and

s y s t em , p r o p e r l y d e s i g n e d a n d a d m i n i s t e r e d , c o u l d h a v e g r e a t p o t e n t i a l f o r e d u c a -

tion, increasing the student's range of choices, his sense of freedom, his motiva-

t i on , an d h i s in t e l l e c t u a l g r a s p * * * ~ * . S u c h a s y s t e m co u l d g r o w i n d e f i n i te l y ,

g r a d u a l l y i n c l u d i n g m o r e a n d m o r e o f t h e ~ r l d ' s w r i t t e n k n o w l ed g e . H o w e v e r , i t s

internal file structure would have to be built to accept growth, change and compl ex

informati onal arr angements. The ELF is such a file structure.

Films, sound recordings, and video recording s are also linear strings, bas-

ically for mechan ical reasons. But theses, too, can now be arranged as non-lin ear

systems-- for instance, lattices-- for editing purposes, or for displa y with dif-

ferent emphasis. (This would natural ly require computer control, using the ELF or

a related system, and various cartr idge or re-rec ordin g devices.) The hyperfi lm--

a browsable or vari-s equenc ed movie-- is only one of the p~ssible h yperm edia that

require our attention.

So much for what we can create afresh with this structure. What about the

things that have already been around awhile?

The physica l universe is not all that decays. So do abstractio ns and cate-

gories. Huma n ideas, science, scholarship and language are constant ly collapsing



14/17

and unfoldi ng. Any field, and the corpus of all fields, is a bundle of relation-

ships subject to all kinds of twists, inversions, involutio ns and rearrangement :

t h e s e c h a n g e s a r e f r e q u e n t b u t u n p r e d i c t a b l e . R e c a l l t h a t c o m p u t e r s , o n c e a b r a n c h

of mathem atics, are now their own field (but the developme nt of fluid logic indi-

c a t e s a p o s s i b l e m e r g e r w i t h t h e a r t o f w i n d i n s t r u m e n t s ) . S o c i a l r e l a t i o n s , p s y -

c h o l i n g u i s t i c s a n d p s y c h o n o m i c s a r e n e w f i e ld s , e v e n t h o u g h t h e y r e s t o n n o s p e c i a l

d i s c o v e r i e s ; p o l i t i c a l e c o n o m y , n a t u r a l h i s t o r y a n d s o c i a l e th i c s ar e go n e. W i t h i n

a given area, too, the subhead ings of importan ce are in constant flux. In the so-

c i a l s c i e n c e s , f o r i n st a n c e , t h e t o p i c h e a d i n g s o f t h e n i n e t e e n - t h i r t i e s n o w s o u n d

quaint.

W h i l e t h e d i s a p p e a r a n c e a n d u p - e n d i n g o f c a t e g o r i e s a n d s u b j e c t s m a y b e e r -

ratic,, it never stops; and the mean ing of this for informat ion ret rieva l sho uld be

clear. Last week's categor ies, perhaps last night' s field, may be gone today. To

t h e e x t e n t t h a t i n f o r m a t i o n r e t r i e v a l i s c o n c e r n e d w i t h s e e k i n g t r u e or i d e a l o r

p e r m a n e n t c o d e s a n d c a te g o r i e s - - a n d e v e n t he m o s t s o p h i s t i c a t e d r o l e i n d i c a t o r

syntaxes are a form of this endeavo r-- to this extent, infor matio n retrieval seems

to me to be fundamenta lly mistaken. The categories are chime rical (or temporal) and

o u r c a t e g o r i z a t i o n s y s t e m s m us t e v o l v e as t h e y d o. I n f o r m a t i o n s y s t e m s m u s t h a v e

built in the capa city to accept the new categ oriz atio n systems as they evolve from,

or outside, the framew ork of the old. Not just the new materi al, but the capac ity

for new arrangeme nts and indefin ite rear rangem ents of the old, must be possible.

In this light, the ELF, inde finit ely revis ible and unpert urbed by changes in over-

a l l s t r u c t u r a l r e l a t i o n s , o f f e r s s o m e p r o m i s e.

There is, then, a general rationa le. I believ e that such a syst em as the ELF

a c t u a l l y t i es i n b e t t e r t h a n a n y t h i n g p r e v i o u s l y u s e d w i t h t h e a c t u a l p r o c e s s e s b y

w h i c h t h o u g h t i s p r o g r e s s i v e l y o r g a n i z e d , w h e t h e r i n t o s t or i e s o r h y p e r t e x t o r l i-

b r a r y c a t e g o r i es . T h u s i t m a y h e l p i n t e g r at e , f o r h u m a n u n d e r s t a n d i n g , b o d i e s o f

m a t e r i a l s o d i v e r s e l y c o n n e c t e d t h a t t h e y c o ul d n o t b e u n t a n g l e d b y t h e u n a i d e d m i nd .

F o r b o t h l o g i s t i c a n d p s y c h o l o g i c a l r e a s o n s i t s h o ul d b e a n i m p o r t a n t a d j u n c t t o

i m a g i n a t i v e , i n t e g r a t i n g a n d c r e a t i v e e n t e r p r is e s . I t i s u s e f u l w h e r e r e l a t i o n s h i p s

a r e u nc l e a r ; w h e r e c o n t i n g e n c i e s a n d t a s ks a r e u n d e f i n e d a n d u n p r e d i c t a b l e ; w h e r e

the structures or final outcome it must r eprese nt are not yet folly known; where we

d o n o t k n o w t h e f i l e ' s u l t i m a t e a r r a n g e m e n t ; w h e r e w e d o n o t k n o w w h a t p a r t s o f t h e

file are most important; or wher e things are in perma nent and unpred icta ble flux.

Perhap s this includes more places than we think. And perhaps here, as in biology,

the only ultim ate s tructu re is change itself.

C O N C L U S I O N

T h i s p a p e r h a s p r o p o s e d a d i f f e r e n t k i n d o f s t r u c t u r e f o r h a n d l i n g i n f o r m a -

tion.

E s s e n t i a l l y i t i s a f i l e w i t h c e r t a i n s t o r a g e p r o v i s i o n s w h i c h , c o m b i n e d , p e r -

mit the file's contents to be arranged any -which- way, and in any number of ways at

o n c e . A s et o f m a n i p u l a t i o n f u n c t i o n s pe r m i t s m a k i n g c h a n g e s or k e e p i n g t r a c k o f

d e v e l o p m e n t s . T h e f i l e i s c a p a b l e o f m a i n t a i n i n g m a n y d i f f e r e n t a r r a n g e m e n t s a t th e

s a m e t i me , m a n y o f w h i c h m a y b e d o r m a n t. T h i s m a k es o r d i n a r y m e a s u r e s o f e f f i c i e n c y

i n a p p r o p r i a te ; a s w i t h h i g h f i d e l i t y m u s i c s y s t e m s , e n r i c h m e n t i s d e r i v e d f r o m t he

lavish use of surplus capacity.

The key ideas of the system are the inter -link ing of different lists, regard-

l e ss o f s e q u e n c e o r a d d i t i o n s ; t h e r e - c o n f i g u r a b l e c h a r a c t e r o f a l i s t c o m p l e x i n t o

any humanly con ceivab le forms; and the ability to make cop ies of a whol e list, or



15/17

list complex-- in prolif eratio n, at will-- to record its sequence, content s or ar-

r a n g e m e n t a t a g l v e n m o m e n t . T h e E v o l u t i o n a r y L is t F i l e i s a m e m b e r o f th e c l a s s

o f e v o l u t i o n a r y f i l e s t r u c t u r e s ; a n d i ts p a r t i c u l a r a d v a n t a g e s a r e t h o u g h t t o b e

p s y c h o l o g i c a l , n o t t e c h n i c al . D e s p i t e t h i s f i l e s a d a p t a b i l i t y t o c o m p l e x p u r p o s e s ,

i t h a s t h e a d v a n t a g e o f b e i n g c o n c e p t u a l l y v e r y s i m p l e . I t s s t r u c t u r e i s c o m p l e t e ,

closed, and unified as a concept. This is its psych ologi cal virtue. Its use can

be easily ta ught to people who do not unde rsta nd computers . We can use it to try

o u t c o m b i n a t i o n s t h a t i n t e r e s t u s , t o m a k e a l t e r n a t i v e s c l e a r i n t h e i r d e t a i l s a n d

r e l a t i o n s h i p s , t o k e e p t r a c k o f d e v e l o p m e n t s a s t h e y o c cu r , t o s k e t c W t h i n g s w e

k n o w , l i k e o r c u r r e n t l y r e q u i r e ; a n d i t w i l l s t a n d b y f o r m o d i f i c a t i o n s . I t c a n b e

e x t e n d e d f o r a l l s o r t s o f p u r p o s e s , a n d i m p l e m e n t e d o r i n c o r p o r a t e d i n a n y p ro -

g r a m m i n g l a n g u a g e .

T h e r e a r e p r o b a b l y v a r i o u s p o s s i b l e f i l e s t r u c t u r e s t h a t w i l l b e u s e f u l i n

aiding crea tive thought. This one operat es, as it were, on lists that hook to-

g e t h e r s i d e w a y s , a n d th e i r c op i e s . T h e r e m a y b e m a n y m o re .

* The Bus h Rap id S e lec to r 2 i s a pow er fu l m ic ro f i l m in s t ru -

m en t , bu t i t is no t s u i t ed to id ios yncr a t i c pe r s ona l u s es , no r

to evo lu t ionary m od i f i ca t ion , a s des c r ibed .

** I t i s be l i eved tha t th i s accoun t i s r eas onab ly co r r ec t

fo r s uch w r i t e r s a s To l s toy , W ins ton Church i l l and K ather ine

A nne P or te r . Thos e w ho can adhere to a p r io r ou t l ine

fa i th fu l ly , l ike J am es F en im or e Cooper , t end to be e i the r

hacks o r p rod ig res , and do no t need th i s s ys tem

*** F or a po ignan t , m ordan t po r t r aya l o f the w r i t e r ' s

s t rugg le , the r eader i s d i r ec te d to G orey ' s The U ns t rung

Harp , or Mr Earba ss Writer.s a Novel .

**** A n ELF m igh t even be cons s t ru c ted ou t o f ca rds ,

b locks, s t i cks and s t r ings , u s ing t echn iques o f puppe t ry ,

bu t th i s w ou ld no t be a conven i en t ob jec t .

***** The s ens e of hyper - u s ed here conno tes ex ten -

s ion and genera l i ty ; c f. hyper s pac e . The c r i t e r i on fo r

th i s p r e f ix i s the inab i l i t y o f thes e ob jec t s to be com pr i s e d

s ens ib ly in to l inea r m ed ia , l ike the t ex t s t r ing , o r even

m ed ia o f s om ew hat h ighe~ com plex i ty . The ELF i s a

hyper f i l e .

1Bus h , V ., A s W e M ay Th ink .

: [ h e A t l a n t i c M o n t h l y ,

p. 101-108; July, 1945.

2Hir sch, P. , The Bush :Ropid Select or .

D a t a m a t i o n , p .

56-57; June, 1965.

3 W al lace , E . M ., Exper ien ce w i th ED P S uppor t o f Ind i -

v idua l s ' F il e M ain tenanc e .

P a r a m e t e r s o f I n f o r m a t i o n

S c i e n c e : P r o c e e d i n g s o f t h e A m e r i c a n . D o c u m e n t o t i o n I n s t i-

t u t e

(Amer ica n Doc umen tat ion Ins t i tu te) , p . 259-261; 1/1964.

4 G orey , E . , The U ns t rung H arp ; o r , M r. Earb ras s W r i tes

a Nove l , Duell , S loan and Pea rce, N. Y. ; 1953.

a IBM D ata P roces s ing D iv i s ion , The IBM A dm in i s t r a t ive

Term inal Sys te m, Broc hure 520-1146.

6 IBM Techn ica l P ub l ica t ions D epar tm e n t , 14~0/1460 A d-

m i n i s t r a t i v e T e r m i n a l S y s t e m A p p l i c a t i o n D e s c r i p t i o n ,

W hi te P la ins , N ew Y ork .

T im ber la ke , W . D ., A dm in i s t r a t ive Term ina l S ys tem

(abs t r ac t . )

S T W P P r o c e e d in g s ;

May, 1965.

s F ar r e l l , A . C ., Evo lu t ion o f A u tom ated W r i t ing .

S T W P

P r o c e e d i n g s ;

May, 1965.

Bobrow , D . G . , and Ber t r am , R ., A Com par i s on o f L i s t -

P r o c e s s i n g L a n g u a g e s .

C o m m . A C M ,

p. 231-240; April, 1964.

~0 Comfo rt , W. T., Mult iwor d Lis t I te ms.

C o m m . A C M ,

p. 357-362; June, 1964.

~ W eizenba um , J . , K no t ted L i s t S t ruc tu r es .

C o m m . A C M ,

p. 161-165; Mar., 1962.

~ZP ryw es, N . S ,, and G ray , H . J. , The M ul t i l i s t S ys tem

for Rea l T im e S to rage and Re t r i eva l ,

P r o c e e d i n g s o f I F I P

C o n f e r e n c e ,

p. 112-116; 1962.

~3P ryw es , N . S ., I n te r im Techn ica l Repor t : The O rgan i -

za t ion o f F i l es fo r Com m and and Con t ro l ,

M o o r e S c h o o l

o [ E n g i n e e r i n g ;

March, 1964.

~4 Bac hman , C. W., and Wi ll iam s, S . B. , The Inte grat ed

D a t a S t o r e - - A G e ne r a l P u r p o s e P r o g r a mm i n g S y s t e m f or

Random A cces s M em or ies ,

A F I P S C o n f e r e n c e P r o c e e d i ng s ,

p. 411-422; 1964.

~nG enera l E lect ' r ic Com pute r D epar tm en t , I -D -S : Com -

pany Brochure CPB-425.

,6 G enera l E lec t r i c Com pute r D e par tm en t , I n t roduc t ion

to Inte grat ed Data Store, Comp any Bro chur e CPB-1048; 1965.

'7 Bachm an , C . W ., S o f tw are fo r Random A cces s P roces s -

ing ,

D a t a m a t i o n ;

April, ].965.

' G enera l E lec t r i c Com pute r D epar tm en t , I n teg ra ted D ata

S to re : N ew G enera l E lec t r i c Techn ique fo r O rgan iz in g Bus i -

, less Data ; Janu ary, 1965

'~ Corbin, H. S ., and St ock, G. J . , On-L ine Quer ying via

a D is p lay Cons o le ,

F o u r t h N a t~ o ~ a l S y m p o s i u m o n I n f o r m a -

t :oa

D i s p l a y : T e c h n i c a l S ~ s s io ~ P r o c e e d i n g s ,

p. 127-154; 1964.



16/17

A B A B

\

~ _ _ L _ ~ / ~ r - - ~ - ]

L_ 3 . : ~ \ \ _ _ ~ _ d 3 ' 4

5 " 2

L I N K E D L I S T S L I N K T A B L E

F I G U R I--Zippered lists: l - f o r - I links between

entries are invariant under list permutation.

q

v. 5;

v. 1

_

LIST PATCHING

v.l

I v 3 1

t

TEXT PATCHING

F IG U R 2--Spinolf o f variants: extra versions need

little space.

Sub-Outline

O u t h n e ~

~ ~ Variant

1

/ . ~ - -

~ ~

,~. Subdraf ts

~ ' / ~ . . M a in Draf t ~

. _ ~ I / ' - ~ _ _ - ~ k / L 1

~ ~ ~ 7 ~ Commen ta r i es

. . . . ~ \ ~ / L ~ h i ~ ~ .

- ~ \ ~ \ S u m m a ry . / ' ~ J l - b . .

F I G U R 3---All levels of documentation in the E L F .



17/17

S u b a c t

i n d e x

I

" ~ O u t l i n I " " - .

t

C a t q g o , l e s

f

1

:

I

b _ _ J

/

/

/

S u b - O u t l i n e s

D e m o g r a p h y J

T a b l e

T r e a t y

T a b l e

Sub - -

C h r o n o l o g y U n c e r t a i n C h r o n o io g i es

L a t t i c e V a r ; o n t .

r - . . . . . . . . . . . . . .

- - ~ R e a d i n g

; ' ~ N o t e s

. . . . . / , .

~ ' , ,~ , n t , ~ S u b l e x l s

\

S o u r c e

T e x t

Qu o t a h o n s

F o o t n o t e s F - - : t - 7 " l

r,e

nelsonted_complexinformationproces_77793

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