I’ve just got back from Barcelona (more on that shortly), and have a brief thought on the VMs for you.
Tony Gaffney emailed a few days ago to say that he had posted up his initial thoughts on the Voynich Manuscript to the Ancient Cryptography forum’s Voynich Manuscript topic: overall, his initial code-breaker’s reaction is that everyone else seems to be overcomplicating the issue – the VMs can’t be that tricky, can it?
Alas, for all Tony’s skill and cunning, I believe that he is trying to read the covertext, much as I described here. In poker terms, the VMs is full of “tells“, tiny behavioural tics, mannerisms and rituals that give away what’s going on under the surface: to a code-breaker’s eyes, the problem here is that there are so many tells that it is hard to accept that they all might be valid at the same time, as opposed to being the quirks of (for example) an unknown language. But they are all tells!
All the same, I’ve been prompted (partly by Tony’s desire to see the VMs as a simple object) into wondering whether my own reading of “4o” (as a “subscriptio” token, indicating a word-initial contraction following the first plaintext letter) might be overcomplex. If not that, though, then what kind of thing might “4o” be?
Thinking about it over the weekend, perhaps the simplest explanation might be that it codes for “lo” [‘the’] in the (very probably Italian, & very probably heavily-abbreviated) plaintext. “lo dragone” would then be written something like “4odra[gone]” (depending on how you encipher the rest of the letters). This has the additional benefit of explaining 4o’s ciphertext shape, as the “lo” would be steganographically concealed within the shape of the “4o”, while its very presence would be concealed by running it into the subsequent word (so, “4otedy” rather than “4o tedy“).
I also suspect that the (rarely seen) free-standing “4” is an entirely different letter entirely… but that’s an issue for a different day.
PS: there isn’t a lot of literature on “4o” (“qo” in EVA), but here’s one brief paper (Sazonov 2003) to be going on with.