Developed and reviewed by experts of the EC, IAEA and NEA, input for this report includes information and experience concerning decommissioning cost items and cost-item definitions. The resulting list, colloquially known as “The Yellow Book”, represents a new, uniform and more complete approach to decommissioning costs. It is hoped that the standardised list will be widely accepted and used. It is recognised that at this stage the list has achieved approval in theory but should be further evaluated in practice. Therefore, this report should be viewed as an interim document, to be broadly distributed, discussed and used, and to be finalised, most effectively in a workshop format, after approximately three years. Thereafter, a more definitive and more broadly tested and supported report will be issued.