The Rime Feeorin was the ancient code of the Feeorin by the time of the Mandalorian Wars.
The Rime Feeorin is known to have included the rules that -
Feln, of the Jedi Covenant, was known to break the Rime Feeorin during his time as leader, allowing the Sanctum to be turned into a storehouse for Sith artifacts. After the Sanctum of the Exalted was destroyed, the strictures of the Rime Feeorin ceased to apply, allowing the Feeorin to kill an unarmed Feln with primitive weapons.