[Movie] This Famous Medieval Book May Be a Hoax

[Letieum]

Only if the method is deterministic, otherwise you have a one-way cipher.  ...

From what I understand, the self-referential method relies on selecting a previous word and choosing a modification to apply to that word.
The method isn't very clear about how these two choices are made, but, as mentioned in my previous message, the presence of a choice offers the possibility to encode meaning.

To avoid having a 'one-way cipher', it's sufficient for the reader to be able to determine the previous word used to form the current word, which simply requires framing the process of choosing the previous word