<s>
The	O
Preferred	B-Application
Executable	I-Application
Format	I-Application
is	O
a	O
file	O
format	O
that	O
specifies	O
the	O
format	O
of	O
executable	B-Application
files	I-Application
and	O
other	O
object	B-Language
code	I-Language
.	O
</s>
<s>
PEF	O
executables	B-Application
are	O
also	O
called	O
Code	O
Fragment	O
Manager	O
files	O
(	O
CFM	O
)	O
.	O
</s>
<s>
PEF	O
was	O
developed	O
by	O
Apple	O
Computer	O
for	O
use	O
in	O
its	O
classic	B-Application
Mac	I-Application
OS	I-Application
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
It	O
was	O
optimised	O
for	O
RISC	B-Architecture
processors	I-Architecture
.	O
</s>
<s>
In	O
macOS	B-Application
,	O
the	O
Mach-O	B-Operating_System
file	O
format	O
is	O
the	O
native	O
executable	B-Application
format	O
.	O
</s>
<s>
However	O
,	O
PEF	O
was	O
still	O
supported	O
on	O
PowerPC-based	O
Macintoshes	O
running	O
Mac	B-Application
OS	I-Application
X	O
and	O
was	O
used	O
by	O
some	O
Carbon	B-Operating_System
applications	O
ported	O
from	O
earlier	O
versions	O
for	O
classic	B-Application
Mac	I-Application
OS	I-Application
,	O
so	O
that	O
the	O
same	O
binary	O
could	O
be	O
run	O
on	O
classic	B-Application
Mac	I-Application
OS	I-Application
and	O
Mac	B-Application
OS	I-Application
X	O
.	O
</s>
<s>
BeOS	B-Application
on	O
PowerPC	B-Architecture
systems	O
also	O
uses	O
PEF	O
,	O
although	O
x86	B-Operating_System
systems	O
do	O
not	O
.	O
</s>
