Nope, just like GPS is completely banned. It's not our centre, it's a D of E rule, no resupply, you cant go into a shop. full stop. Same with GPS, if you're seen with one you fail completely.
Same with mobiles, even if it is off, you fail. It seems so silly, why risk not having a mobile in a potentially life threatening situation? I know it's doubtful but im sure they would be useful!!
Same for GPS again - we aren't allowed to use them. Why? We are supposed to be training up for life, and they encourage us to carry on walking etc. but how many of the people on this forum go out without a GPS ? not too many I would say.
It's just silly having all these rules when it just ain't cricket.