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4.7.7 Header Files and Libraries

Pic device specific header and c source files are automatically generated from MPLAB include files, which are published by Microchip with a special requirement that they are only to be used with authentic Microchip devices. This requirement prevents to publish generated header and c source files under the GPL compatible license, so they are located in the non-free directory (see section 2.3). In order to include them in include and library search paths, the —use-non-free command line option should be defined.
NOTE: the compiled code, which use non-free pic device specific libraries, is not GPL compatible!