The introduction of an adjudication board in the Orange Book to take over the Engineer's pre-arbitral decision-making role was an important step in the development of FIDIC contracts and reflected the increasing use of dispute boards internationally. In adopting an amicable settlement stage the Orange Book provided for a three-tier process: adjudication, amicable settlement and, as a last resort, arbitration. Mediation is a feature of many tiered dispute resolution clauses and could be worked into the amicable settlement stage, either by adopting the example mediation rules given in the FIDIC Guidance or using rules such as the ICC Mediation Rules 2017. Clause 20 of the 1999 Books provides for the parties to appoint a dispute adjudication board (clause 20.2) either when a dispute arises or at the outset of the project. The 2017 contracts retain the basic three-tier structure of the 1999 forms but are detailed and fill certain important gaps in the 1999 forms.