Preservation Pressure Points: Evaluating Diverse Evidence for Risk Management -- Establishing a comprehensive understanding of the effectiveness and trustworthiness of a digital repository requires a broad range of evidence. Preservation can be considered as a complex spatial and chronological network of challenges, and associated risks. For example the organisational, financial, technological and operational contexts within which a repository resides and the extent to which it is capable of managing them must be ascertained if an audit is to be able to assert the likelihood of the institution's success. Significant effort must be directed towards the definition of methodologies for identifying appropriate classes of evidence, to their evaluation, and to the attaching of weight to them. Formal means are required to facilitate the analysis and comparison of disparate evidence types in order to enable auditors to accommodate a diverse range of physical, testimonial and experiment-based proof. In addition to binary systems of inquiry (e.g., does the organisation have a mission statement?) auditors must display an ability to distinguish the most persuasive examples from those that provide less substantive evidence of organisational competence. Similarly, if, for instance, a significant proportion of staff reveal that they have no idea of the content of their organisation's mission statement then this must be reflected in the overall organisational assessment. A comprehensive insight, and consequent decision, can only be reached after fully exploring the evidential basis upon which compliance is to be founded. This discussion of evidential appraisal techniques for repository audit reflects the series of pilot audits undertaken by the Digital Curation Centre within a selection of UK data centres and archives, including the Beazley Archive and the British Atmospheric Data Centre.