[openbeos] internal_function

I thought that I had seen everything... I am building some command line tools 
from the GNU suite and I came across a function declaration that looks like 
this:

static int FCT (const CHAR *pattern, const CHAR *string,
        const CHAR *string_end, int no_leading_period, int flags)
     internal_function; 

I have *never* seen this internal_function thing. My copy of Lippman doesn't 
mention it. Can anyone enlighten me?

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