The Incentives and Earned Privileges system determines which prisoners are entitled to privileges such as extra visits, the ability to earn more money in prison jobs and access to in-cell TV.
Under the current system, there are three levels: 'basic', 'standard' and 'enhanced. Each level has certain associated perks which are set by individual prisons but are broadly the same.
Prisoners currently start on 'standard' and may lose or gain a status based on their behaviour.
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Customers are being urged not to eat any of the chocolate.
If approved the increase would trigger a county-wide referendum.