What does it mean when a shopping carts passes yellow lines of a parking lot?

When a Shopping Cart passes A Special Coded Yellow Line in the parking lot it will LOCK the shopping carts, making it unusable until unlocked by a store staff. When this happens Contact a store staff member to help you get it unlocked. The reason some carts lock is to prevent customers from taking the shopping cart off the store premises. Many stores are using this system, to help keep the streets clean of shopping carts, and so customers can always have carts to use! If they didn't use this system carts would end up on the streets and near homes, and none will be at the store for use! Many stores are using this cart system!