This presentation, the fourth of six parts on the practical analysis of significant properties of digital objects, leads participants through a practical exercise to consider the needs of different stakeholders when assessing the properties of the type of digital object considered in the previous exercise, an email message. The presentation was given as part of module 3 of a 5-module course on digital preservation tools for repository managers, presented by the JISC KeepIt project. For more on this and other presentations in this course look for the tag 'KeepIt course' in the project blog http://blogs.ecs.soton.ac.uk/keepit/