This paper is an extended and updated version of the work reported at iPres 2008. Digital preservation activities can only succeed if they go beyond the technical properties of digital objects. They must consider the strategy, policy, goals, and constraints of the institution that undertakes them and take into account the cultural and institutional framework in which data, documents and records are preserved. Furthermore, because organizations differ in many ways, a one-size-fits-all approach cannot be appropriate. Fortunately, organizations involved in digital preservation have created documents describing their policies, strategies, work-flows, plans, and goals to provide guidance. They also have skilled staff who are aware of sometimes unwritten considerations. Within Planets (Farquhar & Hockx-Yu, 2007), a four-year project co-funded by the European Union to address core digital preservation challenges, we have analyzed preservation guiding documents and interviewed staff from libraries, archives, and data centres that are actively engaged in digital preservation. This paper introduces a conceptual model for expressing the core concepts and requirements that appear in preservation guiding documents. It defines a specific vocabulary that institutions can reuse for expressing their own policies and strategies. In addition to providing a conceptual framework, the model and vocabulary support automated preservation planning tools through an XML representation.