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With the release of Mac OS X Snow Leopard, and before that, since the move to 64-bit architectures in general, some software publishers such as Mozilla have used the term Universal to refer to a fat binary that includes tailored builds for both i386 ( 32-bit Intel ) and x86_64 systems.

The same mechanism which is used to select between the custom PowerPC or Intel builds of an application, is also used to select between the 32-bit or 64-bit builds of either PowerPC or Intel architectures.