The document introduces mental health clustering, which uses the Health of the Nations Outcome Scales (HoNOS) and Summary of Assessments of Risk and Need (SARN) to group service users into clusters based on characteristics like needs, acuity, and treatment response. Trained clinicians score individuals on 18 categories from these assessments and the clustering calculator software matches their scores to the appropriate cluster. The calculator provides a percentage match for each cluster to aid clinicians, but does not override their judgment.