Where have we seen a possible "Red Decoder" and "Punched out white holes" in one of Zodiac's communications before.
The '13 Hole' Postcard was mailed by the Zodiac Killer on October 5th 1970, just shy of the one year anniversary of the 340 cipher. In the postcard the Zodiac Killer provided us with his "red crucifix decoder" and "13 punch-holes" in the fabric of the card. This was his very own Dick Tracy descoder. Seagull, a contributor to the Zodiac Killer Site forum, was on the right path when she stated "If I were to attempt to try something like this, to find a hidden message, I think I would start with using the shape of the crosshair symbol for the template. The problem would be to determine a size and whether or not to round the shape or square it off. Even if you managed to hit on the right size and shape, the message could still be coded. But my totally untrained cipher gut tells me that if the 340 can be solved it's might be something as seemingly simplistic as this". It may very well have been this simplistic, with everybody expecting the Zodiac Killer to make his second cipher much harder, after his first cipher was cracked with relative ease. The Zodiac Killer taking the shape of the "red crucifix decoder" as the template, to be coupled with the 13 punch-holes he added to the October 5th 1970 postcard All we had to do was arrange the 13 punch-holes in the shape of a crucifix, so when it was placed over the 340 cipher, a message was revealed. The Zodiac Killer did add a second tier of messages in the 340 cipher, to which he revealed in the following Halloween Card on October 27th 1970. Nobody at the time understood the secret message in the '13 Hole' Postcard, which is why he added the second layer just 22 days later.
Osiris, is the Egyptian god of fertility, alcohol, agriculture, the "afterlife", the dead, resurrection, life, and vegetation in ancient Egyptian religion. This normally wouldn't be relevant, but for the Dick Tracy Decoder Ring (designed to conceal messages or items) and the Dick Tracy Radio Show sponsored by Quaker Oats, which featured the The Black Pearl of Osiris, given to Dick Tracy to hide in the Decoder Ring. This ring had a specific design on its face, split into four quadrants just like the Paradice and Slaves configuration on the Halloween Card. In the top left quadrant is a Zodiac-like design, bearing some similarity to the crosshairs of Zodiac, along with a moon design in the lower left quadrant. "The Dick Tracy Premium was offered in exchange for five box tops of Quaker Puffed Wheat or Rice and one wonders how many uneaten boxes were dismembered by eager kids before the offer expired". See here at the Dick Tracy Depot.
The Dick Tracy Decoder and Dick Tracy Ring were both targeted at chidren from the 1930s onwards - and both may have had an influence on the cereal munching Zodiac in his childhood years - the rudimentary coding of which may have spawned the inspiration in his design of both the '13 Hole' Postcard and Halloween Card in the October of 1970. Many people believed the Zodiac Killer, shaken by the ease to which his first cipher was cracked, devilishly formulated a far more impenetrable cipher the second time round. Yet, it may be the case, that the inspiration for the Bay Area serial killer in his design of the 340 cipher, may have been inspired by nothing more complicated than the cereal boxes of children.
For more on this topic: Zodiac Killer Site forum and ZodiacKiller.com discussion forum.