4.27 The approach to long-list appraisal set out above and in Annex 1 is derived from the Five Case Model and is outlined in more detail in the HM Treasury Business Case Guidance. The focus of the guidance is new public spending for programmes and projects to purchase or deliver goods or services. Similar principles apply when considering interventions which do not require a business case, for example regulatory options or policy options which lead to changes in the use of existing resources. As with all the Green Book guidance, the approach to long-list analysis should be proportionate to an intervention's likely costs, benefits and risks to society and the public sector.