Overview When you start a "Basic" Campaign, you may target it to either Targeted zone or International zone. You can’t change zone of existing Campaign, but you are allowed to retarget 1 the list of zone countries. Each Worker is allowed to take single position only. "speed" setting controls how big is a chance of Campaign to be shown on Jobs page to Worker. Campaign must have at least 30 positions. Geo-targeting International zone Targeted zone Workers from all countries can work on Campaign. Workers from selected countries can work on Campaign. Up to 10 countries can be excluded. Entity Relationship Diagram Campaign with fixed task details Campaign with unique task details [1] Campaign Zone Retargeting Microworkers Blog .