Hello,
take a look at a file named PEcoff.pdf, this is the PE/COFF specification from M$.
Everything you need is explained in chapter 6.6 (the .reloc section). BTW the 6,7 and 8th field are'nt documented... and there's no fields above 11 (0xB).
Here's a link, you'll not have to search for it

:
http://neitsabes.online.fr/docs/pecoff.pdf