I looked through the Undex right now, and began to see something that might be a coincidence... and maybe not?

In the first page of the Undex (The "incomplete" UK edition, Negative 36b), Under C, it says:
"Code, Rule of Four" and on which pages? A black box.

Now the Circle Cipher Steven posted a while ago was solved using each piece = 4th letter, rule of four?

Checking more into the undex with that black box:
Ludovician<Metavician
Sanderson, Eric, The Other
Ward, Mycroft

We know some characters from TRST will appear in the next book.
(I also think that either if the story is set in 2054 or 1854, Mycroft Ward is a possible character to appear since he's from the middle of the 19th century, and might as well "live" longer than a couple of hundred years into the future. This strengthen my own conviction).

What are your thoughts about this?