It is therefore attractive to be able to reflect the need for assurance in particular circumstances. This can be provided by establishing a trust model, which provides for a range of relationships between any two parties exchanging content. Identification of the parties involved in a content exchange is essential at high trust requirement levels. But a public key infrastructure, required for verification of identities, is expensive using the solutions available today. The cost associated with establishing a trust system is considerable, and this is proving an issue in moving the eBook market forward.
Several problems exist with the two existing options for rights languages.
There are no strong conceptual models supporting either language, and both languages have unclear development processes. The World Wide Web Consortium has also shown an interest in how rights should be expressed and is organizing a seminar in Nice on this topic 6 . The Association of American Publishers commissioned a major investigation of eBook requirements and relevant standards during 2000. Working with Andersen Consulting, several AAP member organizations considered requirements for identification, metadata and digital rights management and looked at whether available standards and product offerings met the requirements. The commercial framework for eBooks will force us to address fundamental issues such as what it is to publish and who can publish.