> One yet further inference might be that, as this would be a far more
> refined version of the "4"/"4o" alphabet-hiding mechanism used in various
> North Italian codes circa 1440-1455, it would almost certainly post-date
> them, while still having been devised by the same code-maker: all of which
> would date it to 1455 or later (my two current hypotheses are 1463 and
> 1465).
Although I like the idea, the only problem is that q appears *almost*
exclusively as word-initial (5423 out of 5456 instances!) Why should the
duplet be coding for a character at the begining of words and not elsewhere?