12. This is the risk that there are inaccuracies in the estimates for the support elements of the Change, including: maintenance requirements, MTBF, equipment obsolescence dates, replacement costs, direct costs, labour (and associated) costs. Whether the Change is a Replacement Change or an Addition Change, the cost associated with this category of risks is likely to be an element for consideration when calculating the SPV profit level. Note however that the risk may lead to either an under- or over-estimate of costs and that Replacement Changes in particular may reduce the risk associated with elements of support costs.