they will tell you the activation code word and the location and time to report to.
will also tell you who are in the advance party which will have to report earlier to do some stuff.
you don't have to worry about it if you are not a KAH... PS, PC, OC, CO, CQ, RQ, etc...
just make sure that all your contact number (HP, home, address, etc) are all correct and up-to-date.
nowadays when there is a mob activation, they will inform you via SMS before the flashing green men even appears on TV, so the code word is not that important anymore.