a question abt variable names....

From: shiva (nikhilbhargav_nsit_at_indiatimes.com)
Date: 01/25/05 

Date: 25 Jan 2005 04:25:19 -0800

hi,

I have seen many functions andvariables in kernel code defines as
__XXXX()/__XXXXX. I know that these refer to kernel defintions but i
want to
know why are the variables in this fashion and also what difference is
between
declaring

__XXXX and _XXXX

Thanks,

shiva