New tournament rules are out.
Basic and Advanced tournament structures (rounds and cuts)
They state you can mark your dice now (I think that's new?)
And this section, from all the dice threads:
Sharing Components
Before a tournament round begins, any player may request that a single range
ruler, set of maneuver templates, and/or each other’s dice be shared for the
duration of the round. Any decisions are subject to review by a marshal or a judge.