I read in a Black Library catalogue the other day that the HH books had different colour lettering to distinguish 'editions'. I'm guessing this means different printings but I"m not sure. Does anyone know what the different colour codes are (ie which is 1st printing, which is 2nd etc). They also seem to ahve different coloured stripes at the top of each book's spine.

Looking at the books in my local GW retailer there are the first 3 books, with bronze cover letterin and red colour bars, the 4th book with silver lettering and a green stripe. Fulgrim has bronze again but a blue stripe and the latest book has gold lettering with a green stripe again.

Apparently this all means something to collectors but does anyone know what? Can anyone decode these? And before you ask- yes, I've checked for printing numbers inside the cover.