I'm still learning these terms but by "kill line" I am assuming you mean the PC is cocked. Either way, if someone is packing your chute for you (you rented for example), how are you supposed to know if your brakes were stowed, if the PC was cocked and the slider was opened back up? You can't see these things once the rig has been fully packed.
Just my little 3 cents. I am complete novice in this business, made just 6 jumps and an AFF student for right now, but I think there are at least two things you can easily check even if your rig is closed, brakes and PC cocked. Little hard for brakes though, but possible and just easy for PC kill line. Anybody, correct me if I am wrong!
This is not a notation, this is just guess and my question. I am learning here.