Random Deathmatch (RDM) is
when a player kills 1 or more people without a valid reason or an rp reason behind it. For example a player is walking around doing nothing to harm you or our not even acknowledging you but you kill them careless and think you should shoot some more people for fun this would be faced with a warn/kick or even a ban it depends on the severity of the RDM. If you are a mugger and shout give me all your money to them and they run off or don't do as you say then you have a reason to kill them and it wouldn't be an RDM. Or an RDM scenario if someone enters your house/shop and you haven't CLEARLY marked ENTER = KOS with the text tool and you just kill them for entering while your building or doing something in there. Or I am walking along minding my own business and a player comes up to me and shots me then runs away.

New Life Rule (NLR) is
when a player is killed and then NLR comes in to play after the player has been killed he has to forget the passed memories and is to not return to the scene of death until the NLR timer is up this prevents Revenge Kill which is also breaking the rules of NLR. This is used for RolePlay and if NLR is broken it is classed as fail RolePlay too. The punishment can be a Warn/Kick/Ban again depending on the severity.

MetaGaming is
when a team/group of players use a 3rd party program to communicate or they use OCC to communicate about things happening in-game/ in-game events. This can also be defined as "Ghosting" on ZARP it is limited to strictly the OOC so you can use 3rd party programs to communicate. The rule has been placed to stop other players from gaining an advantage over ZARP gameplay because other players won't know where the player is or what they are doing. For example someone is selling something and announces it using // Come to my shop! when is should correctly be announced buy using /advert Come To My Shop! Or another example is someone is raiding a players house and the player tells his friend come and help me I'm being raided.