Collaboration ranged from urging the civilian population to remain calm and accept foreign occupation without conflict, organizing trade, production, financial and economic support to joining various branches of the armed forces of the Axis powers or special "national" military units fighting under their command.
Requirements for collaboration
The Nazis did not consider everyone equally fit for cooperation. Even people from closely related nations were often valued differently in accordance with Nazi racial theories.The Jews were considered to be worst of all nations and thus unfit for cooperation, although some were used in concentration camps as Kapos to report on other prisoners and enforce order. Others governed ghettos and helped organize deportations to extermination camps (Jewish Ghetto Police).