<s>
XAR	B-Application
(	O
short	O
for	O
eXtensible	O
ARchive	O
format	O
)	O
is	O
an	O
open	O
source	O
file	B-Application
archiver	I-Application
and	O
the	O
archiver	O
’s	O
file	O
format	O
.	O
</s>
<s>
It	O
was	O
created	O
within	O
the	O
OpenDarwin	O
project	O
and	O
is	O
used	O
in	O
macOS	B-Operating_System
X	I-Operating_System
10.5	O
and	O
up	O
for	O
software	O
installation	O
routines	O
,	O
as	O
well	O
as	O
browser	O
extensions	O
in	O
Safari	B-Application
5.0	O
and	O
up	O
.	O
</s>
<s>
Xar	B-Application
replaced	O
the	O
use	O
of	O
gzipped	O
pax	B-Device
files	I-Device
.	O
</s>
<s>
One	O
development	O
branch	O
of	O
RPM	B-Application
,	O
RPM5	O
,	O
uses	O
xar	B-Application
.	O
</s>
<s>
Offset#	O
Size(in bytes )	O
Purpose	O
0	O
4	O
File	O
signature	O
used	O
to	O
identify	O
the	O
file	O
format	O
as	O
Xar.This	O
should	O
always	O
equal	O
xar	B-Application
!	O
</s>
<s>
4	O
2	O
Header	O
size	O
6	O
2	O
Version	O
of	O
Xar	B-Application
format	O
to	O
use.Currently	O
there	O
is	O
only	O
version	O
1.88Length	O
of	O
the	O
TOC	O
compressed	O
data.168Length	O
of	O
the	O
TOC	O
uncompressed	O
data.244Checksum	O
algorithm	O
:	O
</s>
<s>
Xar	B-Application
is	O
different	O
from	O
cpio	B-Application
,	O
tar	B-Application
or	O
ar	B-Application
in	O
that	O
it	O
stores	O
the	O
TOC	O
(	O
table	O
of	O
contents	O
)	O
in	O
the	O
beginning	O
of	O
the	O
file	O
,	O
making	O
appending	O
to	O
an	O
archive	O
more	O
complicated	O
,	O
but	O
making	O
it	O
unnecessary	O
to	O
scan	O
through	O
the	O
archive	O
to	O
extract	O
an	O
individual	O
contained	O
file	O
.	O
</s>
<s>
The	O
table	O
of	O
contents	O
is	O
stored	O
as	O
a	O
zlib	B-Language
compressed	O
,	O
UTF-8	O
encoded	O
,	O
XML	B-Protocol
document	I-Protocol
.	O
</s>
<s>
Each	O
file	O
that	O
is	O
stored	O
in	O
the	O
Xar	B-Application
is	O
independently	O
compressed/encoded	O
.	O
</s>
<s>
This	O
gives	O
the	O
ability	O
to	O
have	O
the	O
file(s )	O
encoded	O
using	O
gzip	B-Application
while	O
having	O
another	O
file	O
in	O
the	O
same	O
archive	O
encoded	O
using	O
a	O
different	O
method	O
such	O
as	O
bzip2	B-Application
.	O
</s>
<s>
On	O
some	O
systems	O
the	O
archive	O
member	O
can	O
also	O
be	O
encoded	O
by	O
xz	B-Language
or	O
lzma	B-General_Concept
compression	O
method	O
.	O
</s>
