The PEN & PAD clinical workstation is for use by clinicians for direct patient care. It is based on a highly structured and detailed medical record but is intended to be simple and intuitive to use, allowing clinicians to summarise and view information in many ways, and quickly enter information through structured forms. It also provides mechanisms for tailoring the system to individual users without compromising its overall integrity. This has been achieved by following a process of user centred design and by developing a novel formalism, Structured Meta Knowledge, to represent the terminological knowledge, the medical record, and pragmatic knowledge about clinical practice.