Jacopo Silvestri's 1526 Opus novum discussed the Caesar cipher and the author recommended the use of a cipher disc for working with the key. In the depiction of a cipher disc shown above, note that Silvestri's alphabet key lacked the letters j, v, w, and y. "The three marks following Z on the disc represent: the ampersand (& = et); a symbol commonly used in mediaeval Latin to mean us or um at the end of words (e.g. plurib9 = pluribus), or com, con, cum, or cun at the beginning of words (e.g. 9cedo = concedo); and a symbol used for rum, the ending of the Latin genitive plural (illo# = illorum). The zigzag in the center of the figure is supposed to be a little handle to turn the movable disc" (@ Arnold 98).

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