The source code of free Mac OS X 10.7.4 modules has been published.

Apple has published the source code for the open source component of Mac OS X 10.7.4.

Sources are published under various licenses: APSL, BSD, GPL, LGPL, Apache and others.

You can find and study here www.opensource.apple.com/release/mac-os-x-1074
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Remember that your final products that use the source code of the applications, should also should be desirable to publish open source!