If you play as a class in a Battlefield 3 map, obviously whatever class you spawn in as will receive time spent as that class towards the service medal. But what happens when you pick up another kit?
For example, if I spawn in as an Engineer, then run out of ammo and pick up a Recon kit, does my play time from then on go towards Engineer or Recon? I would think it would go towards Recon, however, visibly, my character will still appear to be an Engineer, just one holding a sniper rifle. This leads me to wonder which one actually receives the play time.