Minerva's Morse Code

The books sent to the orphanage by William Minerva are all very subtle messages for the kids, from what the orphanage wants to do with the kids to how to survive should they manage to escape. Minerva's stamp (ex libris) on the inner front cover of selected books has imperfections on the ring surrounding its owl emblem that, upon closer examination, spell out words in Morse code, for instance, and that is the  least  hidden of his messages.

These ex libris in the books were discovered by Phil and was further exposed by Emma. The following are the terms that can be seen.

Promise
This is the Promised Contract that the world was split. One for the Human world and the other for the Demon world. Chapter 47-48

We shall make a treaty as follows:
 * 1) Humans won't hunt Demons anymore.
 * 2) Demons won't hunt Humans either.
 * 3) The world they live (Earth) in is divided in two.
 * 4) Crossing the border between the two worlds is forbidden.