For the benefit of everyone, I just wanted to clear up what the protocol for attacking other PCs is. Especially due to the latest decree.
**EDIT: Okay, the question was: Is it required that you give another PC an IC warning before attacking him/her? **
I understand that you must set the other person to hostile (an OOC action). I also understand that you must have a justifiable IC reason.
I thought that you should also always give the person an IC warning/chance to react rather than just letting arrows fly once they were glowing red. This gives them a chance to run, prepare to fight, or roleplay their way out of it. So, basically there would be NO attacking PCs "on sight", but rather after a fair IC warning. (Although that might just be a quick 'Prepare to die!" or something similar).
However, I could also see the argument that "I am a good elf and she was drow" as justifiable. Knowing that the other char is a PC or DM possessed is OOC. IC you just see a long-hated enemy, so you might attack immediately (or run immediately).
I wanted to clear this up since particularly with the Monstrous Races ban, it explicitly says "[monsters will be] killed on sight."
Thanks
ps. To any goblin PCs out there, my warning will be a "warning shot" (with my bow) that may OR may not miss j/k :D