Poe was a fan of cryptography and a fan cracked the code on the poster:
“…based on the story The Gold Bug by Poe. That is what I used to figure out what the symbols represented. The text/symbols are based on cryptology. If you turn the poster to the left in the center it says The Dead Weather. The long string of text says “With Harlem July Thirty First The Filmore.” Lower left says “Poster by Rob Jones at Animalrummycom.” Center says “DCTSEVEN.” the only symbol I’m not sure about is the one that looks like joined 9’s. Lower Right Says “Printed by D and L in Seattle WA.”