<s>
ARC	B-Application
is	O
a	O
lossless	B-Algorithm
data	I-Algorithm
compression	I-Algorithm
and	O
archival	B-Application
format	O
by	O
System	O
Enhancement	O
Associates	O
(	O
SEA	O
)	O
.	O
</s>
<s>
The	O
file	O
format	O
and	O
the	O
program	O
were	O
both	O
called	O
ARC	B-Application
.	O
</s>
<s>
ARC	B-Application
was	O
extremely	O
popular	O
during	O
the	O
early	O
days	O
of	O
the	O
dial-up	O
BBS	B-Application
.	O
</s>
<s>
ARC	B-Application
was	O
convenient	O
as	O
it	O
combined	O
the	O
functions	O
of	O
the	O
SQ	B-Application
program	I-Application
to	O
compress	O
files	O
and	O
the	O
LU	O
program	O
to	O
create	O
.LBR	B-Application
archives	I-Application
of	O
multiple	O
files	O
.	O
</s>
<s>
The	O
format	O
was	O
later	O
replaced	O
by	O
the	O
ZIP	B-General_Concept
format	O
,	O
which	O
offered	O
better	O
compression	O
ratios	O
and	O
the	O
ability	O
to	O
retain	O
directory	O
structures	O
through	O
the	O
compression/decompression	O
process	O
.	O
</s>
<s>
The	O
.arc	B-Application
filename	O
extension	O
is	O
often	O
used	O
for	O
several	O
unrelated	O
file	O
archive-like	O
file	O
types	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
Internet	O
Archive	O
used	O
its	O
own	O
ARC	B-Application
format	O
to	O
store	O
multiple	O
web	O
resources	O
into	O
a	O
single	O
file	O
.	O
</s>
<s>
The	O
FreeArc	B-Application
archiver	O
also	O
uses	O
.arc	B-Application
extension	O
,	O
but	O
uses	O
a	O
completely	O
different	O
file	O
format	O
.	O
</s>
<s>
Nintendo	O
uses	O
an	O
unrelated	O
"	O
ARC	B-Application
"	O
format	O
for	O
resources	O
,	O
such	O
as	O
MIDI	O
,	O
voice	O
samples	O
,	O
or	O
text	O
,	O
in	O
GameCube	O
and	O
Wii	O
games	O
.	O
</s>
<s>
Several	O
unofficial	O
extractors	O
exist	O
for	O
this	O
type	O
of	O
ARC	B-Application
file	I-Application
.	O
</s>
<s>
In	O
1985	O
,	O
Thom	B-Application
Henderson	I-Application
of	O
System	O
Enhancement	O
Associates	O
wrote	O
a	O
program	O
called	O
ARC	B-Application
,	O
based	O
on	O
earlier	O
programs	O
such	O
as	O
ar	B-Application
,	O
that	O
not	O
only	O
grouped	O
files	O
into	O
a	O
single	O
archive	O
file	O
but	O
also	O
compressed	O
them	O
to	O
save	O
disk	O
space	O
,	O
a	O
feature	O
of	O
great	O
importance	O
on	O
early	O
personal	O
computers	O
,	O
where	O
space	O
was	O
very	O
limited	O
and	O
modem	O
transmission	O
speeds	O
were	O
very	O
slow	O
.	O
</s>
<s>
The	O
archive	O
files	O
produced	O
by	O
ARC	B-Application
had	O
file	O
names	O
ending	O
in	O
"	O
.ARC	B-Application
"	O
and	O
were	O
thus	O
sometimes	O
called	O
"	O
arc	B-Application
files	I-Application
"	O
.	O
</s>
<s>
The	O
source	O
code	O
for	O
ARC	B-Application
was	O
released	O
by	O
SEA	O
in	O
1986	O
and	O
subsequently	O
ported	O
to	O
Unix	B-Application
and	O
Atari	B-Device
ST	I-Device
in	O
1987	O
by	O
Howard	O
Chu	O
.	O
</s>
<s>
This	O
more	O
portable	O
codebase	B-General_Concept
was	O
subsequently	O
ported	O
to	O
other	O
platforms	O
,	O
including	O
VAX/VMS	B-Operating_System
and	O
IBM	B-Device
System/370	I-Device
mainframes	O
.	O
</s>
<s>
Howard	O
's	O
work	O
was	O
also	O
the	O
first	O
to	O
disprove	O
the	O
prevalent	O
belief	O
that	O
Lempel-Ziv	B-Algorithm
encoded	O
files	O
could	O
not	O
be	O
further	O
compressed	O
.	O
</s>
<s>
Additional	O
compression	O
could	O
be	O
achieved	O
by	O
using	O
Huffman	B-General_Concept
coding	I-General_Concept
on	O
the	O
LZW	B-Algorithm
data	O
,	O
and	O
Howard	O
's	O
version	O
of	O
ARC	B-Application
was	O
the	O
first	O
program	O
to	O
demonstrate	O
this	O
property	O
.	O
</s>
<s>
These	O
files	O
worked	O
with	O
the	O
archive	O
file	O
format	O
used	O
by	O
ARC	B-Application
and	O
were	O
significantly	O
faster	O
than	O
ARC	B-Application
on	O
the	O
IBM-PC	O
platform	O
due	O
to	O
selective	O
assembly-language	O
coding	O
.	O
</s>
<s>
Following	O
the	O
System	O
Enhancement	O
Associates	O
,	O
Inc	O
.	O
vs	O
PKWARE	O
Inc	O
.	O
and	O
Phillip	O
W	O
.	O
Katz	O
lawsuit	O
,	O
SEA	O
withdrew	O
from	O
the	O
shareware	O
market	O
and	O
developed	O
ARC+Plus	O
.	O
</s>
<s>
The	O
ARC	B-Application
format	O
is	O
no	O
longer	O
common	O
on	O
PC	O
desktops	O
,	O
but	O
most	O
antivirus	B-Application
scanners	I-Application
can	O
still	O
uncompress	O
any	O
ARC	B-Application
archives	O
found	O
in	O
order	O
to	O
detect	O
viruses	O
within	O
the	O
compressed	O
files	O
.	O
</s>
<s>
In	O
the	O
late	O
1980s	O
a	O
dispute	O
arose	O
between	O
SEA	O
,	O
maker	O
of	O
the	O
ARC	B-Application
program	O
,	O
and	O
PKWARE	O
,	O
Inc	O
.	O
(	O
Phil	O
Katz	O
Software	O
)	O
.	O
</s>
<s>
An	O
independent	O
software	O
expert	O
,	O
John	O
Navas	O
,	O
was	O
appointed	O
by	O
the	O
court	O
to	O
compare	O
the	O
two	O
programs	O
,	O
and	O
stated	O
that	O
PKARC	O
was	O
a	O
derivative	O
work	O
of	O
ARC	B-Application
,	O
pointing	O
out	O
that	O
comments	O
in	O
both	O
programs	O
were	O
often	O
identical	O
,	O
including	O
spelling	O
errors	O
.	O
</s>
<s>
On	O
August	O
2	O
,	O
1988	O
,	O
the	O
plaintiff	O
and	O
defendants	O
announced	O
a	O
settlement	O
of	O
the	O
lawsuit	O
,	O
which	O
included	O
a	O
Confidential	O
Cross-License	O
Agreement	O
under	O
which	O
SEA	O
licensed	O
PKWARE	O
for	O
all	O
the	O
ARC-compatible	O
programs	O
published	O
by	O
PKWARE	O
during	O
the	O
period	O
beginning	O
with	O
the	O
first	O
release	O
of	O
PKXARC	O
in	O
late	O
1985	O
through	O
July	O
31	O
,	O
1988	O
,	O
in	O
return	O
for	O
,	O
which	O
at	O
the	O
time	O
was	O
an	O
undisclosed	O
payment	O
amount	O
.	O
</s>
<s>
In	O
the	O
agreement	O
,	O
PKWARE	O
paid	O
SEA	O
to	O
obtain	O
a	O
license	O
that	O
allowed	O
the	O
distribution	O
of	O
PKWARE	O
's	O
ARC-compatible	O
programs	O
until	O
January	O
31	O
,	O
1989	O
,	O
after	O
which	O
PKWARE	O
would	O
not	O
license	O
,	O
publish	O
or	O
distribute	O
any	O
ARC	B-Application
compatible	O
programs	O
or	O
utilities	O
that	O
process	O
ARC	B-Application
compatible	O
files	O
.	O
</s>
<s>
In	O
exchange	O
,	O
PKWARE	O
licensed	O
SEA	O
to	O
use	O
its	O
source	O
code	O
for	O
PKWARE	O
's	O
ARC-compatible	O
programs	O
.	O
</s>
<s>
PKWARE	O
also	O
agreed	O
to	O
cease	O
any	O
use	O
of	O
SEA	O
's	O
trademark	O
"	O
ARC	B-Application
"	O
and	O
to	O
change	O
the	O
names	O
or	O
marks	O
used	O
with	O
PKWARE	O
's	O
programs	O
to	O
non-confusing	O
designations	O
.	O
</s>
<s>
In	O
addition	O
,	O
defendants	O
would	O
pay	O
plaintiff	O
a	O
royalty	O
fee	O
of	O
6.5	O
%	O
of	O
all	O
revenue	O
received	O
for	O
ARC	B-Application
compatible	O
programs	O
on	O
all	O
orders	O
received	O
after	O
the	O
effective	O
date	O
of	O
this	O
Agreement	O
,	O
such	O
revenue	O
including	O
any	O
license	O
fees	O
or	O
shareware	O
registrations	O
received	O
after	O
the	O
expiration	O
of	O
the	O
license	O
,	O
for	O
ARC	B-Application
compatible	O
programs	O
.	O
</s>
<s>
After	O
the	O
lawsuit	O
,	O
PKWARE	O
released	O
one	O
last	O
version	O
of	O
his	O
PKARC	O
and	O
PKXARC	O
utilities	O
under	O
the	O
new	O
names	O
"	O
PKPAK	O
"	O
and	O
"	O
PKUNPAK	O
"	O
,	O
and	O
from	O
then	O
on	O
concentrated	O
on	O
developing	O
the	O
separate	O
programs	O
PKZIP	B-Application
and	O
PKUNZIP	B-Application
,	O
which	O
were	O
based	O
on	O
new	O
and	O
different	O
file	B-General_Concept
compression	I-General_Concept
techniques	O
and	O
archive	O
file	O
formats	O
.	O
</s>
<s>
protected	O
mark	O
ARC	B-Application
,	O
by	O
turning	O
ARC	B-Application
from	O
noun	O
into	O
verb	O
in	O
the	O
PKPAK	O
manual	O
.	O
</s>
<s>
The	O
SEA	O
vs.	O
PKWARE	O
dispute	O
quickly	O
expanded	O
into	O
one	O
of	O
the	O
largest	O
controversies	O
the	O
BBS	B-Application
world	O
ever	O
saw	O
.	O
</s>
<s>
However	O
,	O
the	O
community	O
largely	O
sided	O
with	O
Katz	O
,	O
due	O
to	O
the	O
fact	O
that	O
SEA	O
was	O
attempting	O
to	O
retroactively	O
declare	O
the	O
ARC	B-Application
file	I-Application
format	O
to	O
be	O
closed	O
and	O
proprietary	O
.	O
</s>
<s>
Katz	O
received	O
positive	O
publicity	O
by	O
releasing	O
the	O
APPNOTE.TXT	O
specification	O
documenting	O
the	O
ZIP	B-General_Concept
file	I-General_Concept
format	I-General_Concept
,	O
and	O
declaring	O
that	O
the	O
ZIP	B-General_Concept
file	I-General_Concept
format	I-General_Concept
would	O
always	O
be	O
free	O
for	O
competing	O
software	O
to	O
implement	O
.	O
</s>
<s>
The	O
net	O
result	O
was	O
that	O
the	O
ARC	B-Application
format	O
quickly	O
dropped	O
out	O
of	O
common	O
use	O
as	O
the	O
predominant	O
compression	O
format	O
that	O
PC-BBSs	O
used	O
for	O
their	O
file	O
archives	O
,	O
and	O
after	O
a	O
brief	O
period	O
of	O
competing	O
formats	O
,	O
the	O
ZIP	B-General_Concept
format	O
was	O
adopted	O
as	O
the	O
predominant	O
standard	O
.	O
</s>
<s>
In	O
an	O
interview	O
,	O
Thom	B-Application
Henderson	I-Application
of	O
SEA	O
said	O
that	O
the	O
main	O
reason	O
he	O
dropped	O
out	O
of	O
software	O
development	O
was	O
because	O
of	O
his	O
inability	O
to	O
emotionally	O
cope	O
with	O
what	O
he	O
claimed	O
was	O
the	O
hate-mail	O
campaign	O
launched	O
against	O
him	O
by	O
Katz	O
.	O
</s>
