My players (and I) are new to ArM, so in launching my saga, I used the library from Semita Errabunda.
Now that they're a bit more familiar with the rules, the recently gauntleted PC magi have spoken disparaginly of their covenant's library. Next session will include the regional Tribunal meeting, which will be held at their covenant, allowing them an opportunity to get involved in the hermetic book trade, potentially expanding their library.
Re-reading the Library chapter of Covenants, I came upon the "Cow and Calf Oath," a Hibernia Tribunal ruling (not yet Grand Tribunal ratified). As an oath, it is an agreement that the purchaser will not sell or give away copies of the book without the sellers permission.
As I read this, I imagined that sellers might not trust the buyer to follow through with the Oath. Not to be too anachronistic, but just as content providers today often embed "Digital Rights Management Software" (DRMS) into their products, distrustful magi might, to prevent unathorized copies of books, enchant them with "Book Rights Management Spell(ware)"
What spells/effects might they cast/enchant into a book before selling it? What would be legal under the code? Would the legality change if the BRMS was disclosed, perhaps on the first page or by some other means?
I'm running a high fantasy saga where, while most common folk don't know much if anything about them, the order is public and has diplomatic relations with the church and other power groups, set in the Provencal tribunal, so I've got a bit of latitude in terms of regional tribunal rulings and such for wiggle room.