PLC (power level compatible) mods are special graphics mods that re-locate all the weapon colours from dirt and rock pallete entries to non dirt and rock pallete enteries. This alowes a powerlevel to modify the dirt pallete entries 12 to 18, 94 to 103 and 176 to 180 and the rock pallete entries 19 to 29 without changing any weapon colours.

Put simply, you can run a powerlevel that changes the dirt and rock colours, without it changing the weapon colours if you use this mod.