<s>
LHA	B-Application
or	O
LZH	O
is	O
a	O
freeware	B-License
compression	B-General_Concept
utility	I-General_Concept
and	O
associated	O
file	O
format	O
.	O
</s>
<s>
It	O
was	O
created	O
in	O
1988	O
by	O
,	O
a	O
doctor	O
and	O
originally	O
named	O
LHarc	B-Application
.	O
</s>
<s>
A	O
complete	O
rewrite	O
of	O
LHarc	B-Application
,	O
tentatively	O
named	O
LHx	O
,	O
was	O
eventually	O
released	O
as	O
LH	O
.	O
</s>
<s>
It	O
was	O
then	O
renamed	O
to	O
LHA	B-Application
to	O
avoid	O
conflicting	O
with	O
the	O
then-new	O
MS-DOS	B-Application
5.0	O
(	O
"	O
load	O
high	O
"	O
)	O
command	O
.	O
</s>
<s>
The	O
original	O
LHA	B-Application
and	O
its	O
Windows	B-Application
port	O
,	O
LHA32	O
,	O
are	O
no	O
longer	O
in	O
development	O
because	O
Yoshizaki	O
is	O
busy	O
at	O
work	O
.	O
</s>
<s>
Although	O
no	O
longer	O
much	O
used	O
in	O
the	O
west	O
,	O
LHA	B-Application
remained	O
popular	O
in	O
Japan	O
until	O
the	O
2000s	O
.	O
</s>
<s>
It	O
was	O
used	O
by	O
id	O
Software	O
to	O
compress	O
installation	O
files	O
for	O
their	O
earlier	O
games	O
,	O
including	O
Doom	B-Application
and	O
Quake	B-Application
.	O
</s>
<s>
Because	O
some	O
versions	O
of	O
LHA	B-Application
have	O
been	O
distributed	O
with	O
source	O
code	O
under	O
the	O
permissive	B-License
license	I-License
,	O
LHA	B-Application
has	O
been	O
ported	O
to	O
many	O
operating	O
systems	O
and	O
is	O
still	O
the	O
main	O
archiving	O
format	O
used	O
on	O
the	O
Amiga	B-Device
computer	I-Device
,	O
although	O
it	O
competed	O
with	O
LZX	B-Device
in	O
the	O
mid	O
1990s	O
.	O
</s>
<s>
This	O
was	O
due	O
to	O
Aminet	B-Device
,	O
the	O
world	O
's	O
largest	O
archive	O
of	O
Amiga-related	O
software	O
and	O
files	O
,	O
standardising	O
on	O
Stefan	O
Boberg	O
's	O
implementation	O
of	O
LHA	B-Application
for	O
the	O
Amiga	B-Device
.	O
</s>
<s>
Microsoft	O
released	O
the	O
Microsoft	O
Compressed	O
(	O
LZH	O
)	O
Folder	O
Add-on	O
,	O
which	O
was	O
designed	O
for	O
the	O
Japanese	O
version	O
of	O
Windows	B-Application
XP	I-Application
.	O
</s>
<s>
The	O
Japanese	O
version	O
of	O
Windows	B-Device
7	I-Device
ships	O
with	O
the	O
LZH	O
folder	O
add-on	O
built-in	O
.	O
</s>
<s>
Users	O
of	O
non-Japanese	O
versions	O
of	O
Windows	B-Device
7	I-Device
Enterprise	O
and	O
Ultimate	O
can	O
also	O
install	O
the	O
LZH	O
folder	O
add-on	O
by	O
installing	O
the	O
optional	O
Japanese	O
language	O
pack	O
from	O
Windows	B-Application
Update	O
.	O
</s>
<s>
In	O
an	O
LZH	O
archive	O
,	O
the	O
compression	B-General_Concept
method	O
is	O
stored	O
as	O
a	O
five-byte	O
text	O
string	O
,	O
e.g.	O
</s>
<s>
LHarc	B-Application
compresses	O
files	O
using	O
an	O
algorithm	O
from	O
Yoshizaki	O
's	O
earlier	O
LZHUF	O
product	O
,	O
which	O
was	O
modified	O
from	O
LZARI	O
developed	O
by	O
,	O
but	O
uses	O
Huffman	B-General_Concept
coding	I-General_Concept
instead	O
of	O
arithmetic	B-Algorithm
coding	I-Algorithm
.	O
</s>
<s>
LZARI	O
uses	O
Lempel	B-Algorithm
–	I-Algorithm
Ziv	I-Algorithm
–	I-Algorithm
Storer	I-Algorithm
–	I-Algorithm
Szymanski	I-Algorithm
with	O
arithmetic	B-Algorithm
coding	I-Algorithm
.	O
</s>
<s>
No	O
compression	B-General_Concept
method	O
is	O
applied	O
to	O
the	O
source	O
data	O
.	O
</s>
<s>
This	O
method	O
is	O
introduced	O
in	O
LHarc	B-Application
version	O
1	O
.	O
</s>
<s>
Dynamic	O
Huffman	B-General_Concept
encoding	I-General_Concept
is	O
used	O
.	O
</s>
<s>
Dynamic	O
Huffman	B-General_Concept
encoding	I-General_Concept
is	O
used	O
.	O
</s>
<s>
Static	O
Huffman	B-General_Concept
encoding	I-General_Concept
is	O
used	O
.	O
</s>
<s>
lh5	O
is	O
first	O
introduced	O
in	O
LHarc	B-Application
2	O
,	O
followed	O
by	O
lh6	O
in	O
LHA	B-Application
2.66	O
(	O
MSDOS	B-Application
)	O
,	O
lh7	O
in	O
LHA	B-Application
2.67	O
beta	O
(	O
MSDOS	B-Application
)	O
.	O
</s>
<s>
LHA	B-Application
itself	O
never	O
compresses	O
into	O
lh4	O
.	O
</s>
<s>
Technically	O
it	O
is	O
not	O
a	O
compression	B-General_Concept
method	O
,	O
but	O
it	O
is	O
used	O
in	O
.LZH	B-Application
archive	O
to	O
indicate	O
that	O
the	O
compressed	O
object	O
is	O
an	O
empty	O
directory	O
.	O
</s>
<s>
Joe	O
Jared	O
extended	O
LZSS	B-Algorithm
to	O
use	O
larger	O
dictionaries	O
.	O
</s>
<s>
These	O
compression	B-General_Concept
methods	O
are	O
created	O
by	O
PMarc	O
,	O
a	O
CP/M	B-Application
archiver	O
created	O
by	O
Miyo	O
.	O
</s>
<s>
No	O
compression	B-General_Concept
method	O
is	O
applied	O
to	O
the	O
source	O
data	O
.	O
</s>
<s>
LArc	O
uses	O
the	O
same	O
file	O
format	O
as	O
.LZH	B-Application
,	O
but	O
was	O
written	O
by	O
Kazuhiko	O
Miki	O
,	O
Haruhiko	O
Okumura	O
and	O
Ken	O
Masuyama	O
,	O
with	O
extension	O
name	O
"	O
.LZS	O
"	O
.	O
</s>
<s>
It	O
uses	O
a	O
binary	B-Language
search	I-Language
tree	I-Language
in	O
the	O
LZ	O
matching	O
.	O
</s>
<s>
No	O
compression	B-General_Concept
method	O
is	O
applied	O
to	O
the	O
source	O
data	O
.	O
</s>
<s>
Because	O
of	O
a	O
bug	O
,	O
DOS	B-Device
time	O
stamps	O
from	O
Level	O
0	O
and	O
1	O
headers	O
after	O
the	O
year	O
2011	O
will	O
be	O
set	O
to	O
1980	O
,	O
meaning	O
that	O
some	O
utilities	O
need	O
to	O
be	O
patched	O
.	O
</s>
<s>
The	O
newer	O
Level	O
2	O
and	O
3	O
headers	O
use	O
a	O
32-bit	O
Unix	B-Operating_System
time	I-Operating_System
instead	O
.	O
</s>
<s>
It	O
suffers	O
from	O
the	O
Year	B-Application
2038	I-Application
problem	I-Application
.	I-Application
</s>
<s>
According	O
to	O
Micco	O
,	O
the	O
author	O
of	O
a	O
popular	O
LHA	B-Application
library	O
UNLHA32.DLL	O
,	O
many	O
LHA	B-Application
implementations	O
do	O
not	O
check	O
for	O
the	O
length	O
of	O
LHA	B-Application
file	O
headers	O
when	O
reading	O
the	O
archive	O
.	O
</s>
<s>
A	O
similar	O
problem	O
exists	O
with	O
ARJ	B-Application
.	O
</s>
