Probably a good idea to keep a copy of the Internationally recognised intercept procedures, in case you are intercepted. Since 9/11 who knows when you may need it. Yes I am aware we should all know them, however we also forget and we cant really afford to get it wrong either, you may only get one chance.
Some countries with sensitive borders it is mandatory to have these on board and at hand.
The search and rescue ground to air signals, would be good info also.
All best kept in a small soft covered file of plastic sheaths.