[Dev-C++] @ symbol at the end of function names?

[<or...@vp...>]

Hi!

I saw in some DLLs and .def files, that there is an @ symbol at the end 
of funtion names, then there is a number after it. I ask, what are they 
for? Why are there these numbers? What purpose do they serve?

Thanks in advance.

--
Greetings,
   Balázs