When the Zodiac Killer created his third lengthy cryptogram (in possibly May, 1971), containing yet another contemporary message about "phony" Eric Weill (and claimed additional "phony" Karl Francis Werner), the Zodiac Killer, this time, made sure his message would not be lost to the hands of time by manufacturing a cryptogram much simpler than the 408 cipher, by allotting just one ciphertext character to each plaintext letter. The only three times he deviated from this technique in the cryptogram was with the bold letter "G" that concluded the word "LISTENING" on the third row, and the letter "T" in "THE" and "FRONT" on the first and fifth row. The Zodiac Killer likely incorporated two deliberate errors on the first row when he used two misspellings within his "This is the Zodiac speaking" introduction. These deliberate misspellings, by adding and subtracting a plaintext letter, very likely created to add minor complexity, and prevent an immediate decoding of his cipher.
Having used the letter "Z" in plaintext for the first time in three cryptograms, it seemed that the Zodiac Killer couldn't resist using the "sun cross" character (similar to his crosshairs) to represent the initial of his pseudonym. This becomes apparent when he uses this individual character to sign off his accompanying letter, rather than the traditional crosshairs or letter "Z".