Polyphonic Cipher?

[nablator]

What if the cipher manuscript is encoded with some kind of a polyphonic cipher, a precursor to ciphers of this kind which were developed starting from the second half of the 15th century?

Actually the most common medieval cipher (next consonant-for-vowel replacement) is polyphonic. You are not allowed to view links. Register or Login to view.

Perhaps the benched diacritical marks could be used to switch from one encoding mode to another?

So you actually mean a "stateful" cipher or code, not a polyphonic one.