If it feels like an Alberti Cipher it is one!

[-JKP-]

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6. There are missing pages. If this is in fact code, which pages would you rip out?
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The removed and missing pages are somewhat accounted for by the correspondence between the various parties documented on Rene Zandbergen's site.

There are mentions of copied pages (ones that were reproduced so that the document as-it-was-at-the-time remained intact), but there are also hints that a few actual pages may, at some point have been shared with others in the hopes of getting a translation and, if I remember correctly, a "booklet" was mentioned, which could perhaps refer to a missing quire (I need to refresh my memory on this correspondence and can't do so until after work, but Rene may have some thoughts on this).