The problem with the term "atypical" Italian diplomatic cipher is that it's vague (it might be clear in your mind, Mark, but that doesn't mean everyone else can see what is in your head), and it's a moving target. People's ideas change all the time.
On Monday, a robin might be an "atypical" duck. On Thursday, an eagle might be an "atypical" duck. The ideas may change in your mind but we are still stuck with a vague term.
So, spell out what kind of cipher it is rather than calling it "atypical".
What is it and what is it not? Then let us decide if it has anything in common with a diplomatic cipher, rather than you deciding for us.
On Monday, a robin might be an "atypical" duck. On Thursday, an eagle might be an "atypical" duck. The ideas may change in your mind but we are still stuck with a vague term.
So, spell out what kind of cipher it is rather than calling it "atypical".
What is it and what is it not? Then let us decide if it has anything in common with a diplomatic cipher, rather than you deciding for us.