__ver must be 3 or the behavior of these functions is undefined.
__filename is as specified by the Large File Summit.
__filedesc is as specified by the Large File Summit.
__stat_buf is as specified by the Large File Summit.
__xstat64(3, __filename, __stat_buf) has the same specification as stat64(__filename, __stat_buf) as specified by the Large File Summit.
__lxstat64(3, __filename, __stat_buf) has the same specification as lstat64(__filename, __stat_buf) as specified by the Large File Summit.
__fxstat64(3, __filedesc, __stat_buf) has the same specification as fstat64(__filedesc, __stat_buf) as specified by the Large File Summit.
__xstat64, __lxstat64, and __fxstat64 are not in the source standard; they are only in the binary standard.
stat64, lstat64, and fstat64 are not in the binary standard; they are only in the source standard.