<s>
In	O
NeXTSTEP	B-Application
,	O
OPENSTEP	B-Operating_System
,	O
GNUstep	B-Application
,	O
and	O
their	O
lineal	O
descendants	O
macOS	B-Application
and	O
iOS	B-Application
,	O
a	O
bundle	B-Application
is	O
a	O
file	B-Application
directory	I-Application
with	O
a	O
defined	O
structure	O
and	O
file	O
extension	O
,	O
allowing	O
related	O
files	O
to	O
be	O
grouped	O
together	O
as	O
a	O
conceptually	O
single	O
item	O
.	O
</s>
<s>
Examples	O
of	O
bundles	B-Application
that	O
contain	O
executable	B-Application
code	I-Application
include	O
applications	B-Application
,	O
frameworks	B-Application
,	O
and	O
plugins	B-Application
.	O
</s>
<s>
This	O
kind	O
of	O
bundle	B-Application
usually	O
contains	O
one	O
file	O
representing	O
executable	B-Application
code	I-Application
,	O
and	O
files	O
that	O
represent	O
resources	O
such	O
as	O
nibs	O
,	O
templates	O
,	O
images	O
,	O
sounds	O
,	O
and	O
other	O
media	O
.	O
</s>
<s>
On	O
some	O
other	O
systems	O
,	O
such	O
as	O
Microsoft	B-Application
Windows	I-Application
,	O
these	O
resources	O
are	O
usually	O
included	O
directly	O
in	O
the	O
executable	B-Application
file	I-Application
itself	O
at	O
compile	O
time	O
.	O
</s>
<s>
On	O
older	O
Macintoshes	O
,	O
a	O
similar	O
technique	O
is	O
used	O
,	O
where	O
additional	O
metadata	O
can	O
be	O
added	O
to	O
a	O
file	O
's	O
resource	B-Operating_System
fork	I-Operating_System
.	O
</s>
<s>
Similar	O
in	O
concept	O
are	O
the	O
application	B-Application
directories	I-Application
used	O
in	O
RISC	B-Operating_System
OS	I-Operating_System
and	O
on	O
the	O
ROX	B-Language
Desktop	I-Language
.	O
</s>
<s>
Examples	O
of	O
bundles	B-Application
that	O
do	O
not	O
contain	O
executable	B-Application
code	I-Application
include	O
document	O
packages	B-Operating_System
(	O
iWork	B-Application
documents	O
)	O
and	O
media	O
libraries	O
(	O
iPhoto	B-Operating_System
Library	O
)	O
.	O
</s>
<s>
Bundles	B-Application
are	O
programmatically	O
accessed	O
with	O
the	O
NSBundle	O
class	O
in	O
Cocoa	B-Operating_System
,	O
NeXTSTEP	B-Application
and	O
GNUstep	B-Application
's	O
Foundation	B-Operating_System
frameworks	B-Application
,	O
and	O
with	O
CFBundle	O
in	O
Core	B-Operating_System
Foundation	I-Operating_System
.	O
</s>
<s>
Bundles	B-Application
often	O
include	O
an	O
file	O
for	O
metadata	O
.	O
</s>
<s>
The	O
Uniform	B-Operating_System
Type	I-Operating_System
Identifier	I-Operating_System
(	O
UTI	O
)	O
for	O
an	O
Apple	O
bundle	B-Application
is	O
com.apple.bundle	O
.	O
</s>
<s>
Application	O
bundles	B-Application
are	O
directory	B-Application
hierarchies	O
,	O
with	O
the	O
top-level	O
directory	B-Application
having	O
a	O
name	O
that	O
ends	O
with	O
a	O
.app	O
extension	O
.	O
</s>
<s>
In	O
an	O
application	O
bundle	B-Application
,	O
the	O
first	O
directory	B-Application
in	O
the	O
bundle	B-Application
underneath	O
the	O
top-level	O
directory	B-Application
is	O
usually	O
named	O
Contents	O
.	O
</s>
<s>
Within	O
Contents	O
there	O
is	O
usually	O
another	O
directory	B-Application
(	O
called	O
MacOS	B-Application
on	O
Macs	O
)	O
,	O
which	O
contains	O
the	O
application	O
's	O
executable	B-Application
code	I-Application
.	O
</s>
<s>
Within	O
the	O
Contents	O
folder	O
there	O
is	O
usually	O
also	O
a	O
directory	B-Application
called	O
Resources	O
,	O
which	O
contains	O
the	O
resources	O
of	O
the	O
application	O
.	O
</s>
<s>
Other	O
common	O
subdirectories	B-Application
include	O
Plugins	B-Application
,	O
Frameworks	B-Application
,	O
and	O
Shared	O
Frameworks	B-Application
.	O
</s>
<s>
The	O
Frameworks	B-Application
directory	B-Application
contains	O
frameworks	B-Application
used	O
by	O
the	O
application	O
,	O
and	O
are	O
used	O
even	O
if	O
another	O
version	O
of	O
the	O
framework	O
exists	O
on	O
the	O
system	O
.	O
</s>
<s>
The	O
Shared	O
Frameworks	B-Application
directory	B-Application
contains	O
frameworks	B-Application
that	O
can	O
be	O
used	O
both	O
by	O
the	O
application	O
that	O
contains	O
them	O
,	O
and	O
other	O
applications	B-Application
;	O
they	O
are	O
used	O
only	O
if	O
a	O
newer	O
version	O
does	O
not	O
exist	O
elsewhere	O
on	O
the	O
system	O
.	O
</s>
<s>
Plugins	B-Application
contains	O
extensible	O
code	O
used	O
by	O
the	O
application	O
.	O
</s>
<s>
By	O
default	O
,	O
the	O
Finder	B-Application
displays	O
application	O
bundles	B-Application
,	O
which	O
can	O
also	O
be	O
referred	O
to	O
as	O
packages	B-Operating_System
,	O
as	O
opaque	O
files	O
with	O
no	O
underlying	O
structure	O
;	O
the	O
contents	O
of	O
the	O
bundle	B-Application
can	O
be	O
shown	O
with	O
the	O
"	O
Show	O
Package	O
Contents	O
"	O
context	O
menu	O
item	O
.	O
</s>
<s>
GNUstep	B-Application
by	O
default	O
uses	O
the	O
name	O
of	O
the	O
application	O
to	O
name	O
the	O
folder	O
that	O
contains	O
application	O
code	O
.	O
</s>
<s>
macOS	B-Application
frameworks	B-Application
are	O
also	O
stored	O
as	O
bundles	B-Application
;	O
the	O
top-level	O
directory	B-Application
of	O
a	O
framework	O
bundle	B-Application
has	O
a	O
name	O
that	O
is	O
the	O
name	O
of	O
the	O
framework	O
followed	O
by	O
the	O
extension	O
.framework	O
.	O
</s>
<s>
In	O
the	O
top-level	O
directory	B-Application
is	O
a	O
Versions	O
directory	B-Application
,	O
with	O
subdirectories	B-Application
for	O
one	O
or	O
more	O
versions	O
of	O
the	O
framework	O
,	O
each	O
subdirectory	B-Application
containing	O
the	O
dynamic	O
library	O
code	O
for	O
the	O
framework	O
,	O
in	O
a	O
file	O
whose	O
name	O
is	O
the	O
same	O
as	O
the	O
name	O
of	O
the	O
framework	O
,	O
possibly	O
with	O
a	O
Headers	O
folder	O
containing	O
header	B-Language
files	I-Language
for	O
the	O
framework	O
,	O
and	O
other	O
subfolders	B-Application
such	O
as	O
Resources	O
.	O
</s>
<s>
The	O
Versions	O
directory	B-Application
also	O
contains	O
a	O
symbolic	O
link	O
Current	O
to	O
the	O
directory	B-Application
for	O
the	O
current	O
version	O
of	O
the	O
framework	O
.	O
</s>
<s>
In	O
the	O
top-level	O
directory	B-Application
are	O
symbolic	O
links	O
to	O
the	O
contents	O
of	O
Versions/Current	O
.	O
</s>
<s>
The	O
Finder	B-Application
displays	O
framework	O
bundles	B-Application
as	O
directories	B-Application
rather	O
than	O
as	O
opaque	O
files	O
.	O
</s>
<s>
Although	O
GNUstep	B-Application
uses	O
frameworks	B-Application
,	O
they	O
are	O
not	O
usually	O
stored	O
as	O
bundles	B-Application
.	O
</s>
<s>
Loadable	O
bundles	B-Application
are	O
bundles	B-Application
which	O
contain	O
code	O
that	O
can	O
be	O
loaded	O
at	O
runtime	O
.	O
</s>
<s>
Loadable	O
bundles	B-Application
usually	O
have	O
the	O
extension	O
.bundle	O
,	O
and	O
are	O
most	O
often	O
used	O
as	O
plug-ins	B-Application
.	O
</s>
<s>
On	O
macOS	B-Application
,	O
there	O
is	O
a	O
way	O
to	O
load	O
bundles	B-Application
even	O
into	O
applications	B-Application
that	O
do	O
not	O
support	O
them	O
,	O
allowing	O
for	O
third	O
party	O
hacks	O
for	O
popular	O
applications	B-Application
,	O
such	O
as	O
Safari	B-Application
and	O
Apple	B-Operating_System
Mail	I-Operating_System
.	O
</s>
<s>
A	O
feature	O
inherited	O
from	O
NeXTSTEP	B-Application
,	O
GNUstep	B-Application
has	O
the	O
interface	O
too	O
.	O
</s>
<s>
By	O
default	O
,	O
the	O
Finder	B-Application
displays	O
loadable	O
bundles	B-Application
,	O
which	O
can	O
also	O
be	O
referred	O
to	O
as	O
packages	B-Operating_System
,	O
as	O
opaque	O
files	O
with	O
no	O
underlying	O
structure	O
;	O
the	O
contents	O
of	O
the	O
bundle	B-Application
can	O
be	O
shown	O
with	O
the	O
"	O
Show	O
Package	O
Contents	O
"	O
context	O
menu	O
item	O
.	O
</s>
<s>
There	O
are	O
many	O
third-party	O
macOS	B-Application
applications	B-Application
which	O
utilize	O
their	O
own	O
custom	O
bundle	B-Application
format	O
(	O
e.g.	O
</s>
<s>
CandyBar	B-Operating_System
.iContainer	O
,	O
Aperture	B-Operating_System
.aplibrary	O
,	O
VMware	B-Operating_System
Fusion	I-Operating_System
.vmwarevm	O
,	O
etc	O
.	O
</s>
<s>
An	O
.lproj	O
file	O
is	O
a	O
bundle	B-Application
that	O
contains	O
localization	B-General_Concept
files	O
for	O
OpenStep	B-Operating_System
,	O
macOS	B-Application
,	O
or	O
GNUstep	B-Application
software	O
.	O
</s>
<s>
These	O
localized	O
files	O
are	O
used	O
by	O
installer	O
makers	O
to	O
customize	O
install	O
packages	B-Operating_System
.	O
</s>
<s>
They	O
are	O
also	O
included	O
in	O
an	O
application	O
bundle	B-Application
.	O
</s>
