This answer contains spoilers… (view spoiler)[In the typed letter to Archie from Vince there are some alphabetical letters missing. Those spell out "Tell your mother I love her." It's never revealed in the book - the reader has a secret code to decipher themselves! We know Vince loved Archie's mom, so it's not a real secret - but fun to decipher! (hide spoiler)]
Heather There's a code that you would miss, but I think you could still figure out what's going on without it.