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Preferred Executable Format
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<p>The Preferred Executable Format is a <a href="/facts/File_format/qrXbwJaH">file format</a> that specifies the format of <a href="/facts/Executable/VSst9eLA">executable</a> files and other <a href="/facts/Object_code/Sht3h4lW">object code</a>. PEF executables are also called Code Fragment Manager files (CFM). </p><p>PEF was developed by <a href="/facts/Apple_Computer/oTJYta3k">Apple Computer</a> for use in its <a href="/facts/Classic_Mac_OS/I5fQq44K">classic Mac OS</a> <a href="/facts/Operating_system/8XTuvMh2">operating system</a>. It was optimised for <a href="/facts/Reduced_instruction_set_computer/aQbGM62p">RISC</a> <a href="/facts/Central_processing_unit/Jxp1bqMV">processors</a>. In <a href="/facts/MacOS/Y93vVpTm">macOS</a>, the <a href="/facts/Mach-O/3agPpt56">Mach-O</a> file format is the native <a href="/facts/Executable/VSst9eLA">executable</a> format. However, PEF was still supported on <a href="/facts/PowerPC/DqmM9y50">PowerPC</a>-based Macintoshes running Mac OS X and was used by some <a href="/facts/Carbon_(computing)/KAIwFWI2">Carbon</a> applications ported from earlier versions for classic Mac OS, so that the same binary could be run on classic Mac OS and Mac OS X. </p><p><a href="/facts/BeOS/tGYfe835">BeOS</a> on PowerPC systems also uses PEF, although <a href="/facts/X86/Kypq5fgu">x86</a> systems do not. </p>