1.21 The level of performance penalty points, and therefore the amount of any financial deduction, is affected by the procedures for monitoring the contracts. Some of the performance measures are relatively straightforward, for example, a positive adjudication following an assault. However, other measures are more ambiguous and allow for a degree of discretion on the part of those responsible for monitoring the contract. For example, most PFI prisons have a performance measure on the number of self-harm incidents which result in an injury to the prisoner. An individual prisoner with a long history of persistent self-harm can have a dramatic effect on performance against that measure even if the prison is taking all possible precautions to control the number of incidents. In such cases, it is important that the contractor and the Controller work together to interpret the contract in a reasonable manner.