What's Up With the Release Date?

Becky: A lot of horror that's being reviewed in those major publications is coming from me too. Becky, thank you so much for joining us. It was really fun. Now let's answer a bookish question from one of our listeners. Dana writes in, i work at a library, and part of my job is shelving the books. I have slowly come to notice that most harlequin paper back romance novels have a date and a four digit number on the spine. They're probably somehow related, but i can't figure out how.