I was inspecting the code of a linux application and i saw the #include in one of the code files. I tried looking it up on opengroup.org but i couldn't find it there, this is what the sys directory looks like: http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/ . I guess it's not standard header file, but i checked it in my /usr/include/sys and it was there.
What does it do and what it is used for ? If you can provide me with some manual for it, i would be grateful. Thanks.