Preferred Executable Format

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Preferred Executable Format
File extension:	none
Uniform Type Identifier:	com.apple.pef-binary
Developed by:	Apple Computer
Type of format:	executable
Container for:	PowerPC executable and object code

The Preferred Executable Format is a file format that specifies the format of executable files and other object code. PEF executables are also called Code Fragment Manager files (CFM).

PEF was developed by Apple Computer for use in its Mac OS operating system. It was optimised for RISC processors. In Mac OS X, the Mach-O file format is the native executable format. However, PEF is still supported on PowerPC-based Macintoshes and is used by some Carbon applications ported from earlier Mac OS versions.

On June 6, 2005 at the annual WWDC, Apple Computer announced that Macintoshes would be switching to the Intel processor starting in 2006. As a result of the switch, PEF was deprecated and it was announced that the PEF binary format would not be supported on Intel Macintoshes except through the Rosetta PowerPC emulation software.

BeOS on PowerPC systems also uses PEF, although x86 systems do not.