The University of Edinburgh and research sponsors are authorised to reproduce and distribute reprints and on-line copies for their purposes notwithstanding any copyright annotation hereon. The views and conclusions contained herein are the author’s and shouldn’t be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of other parties.

The aim of this paper is to show how the rationale behind a plan can be recorded in the plan itself. The model which underlies the I-X framework will be described in detail, focussing on annotations. It is there that a planner can record the justifications for including components into the plan. Recording rationale information of this type can be used for a number of purposes in the life cycle of a plan, including plan indexing and retrieval, failure recovery, plan explanation and establishing trust as explained in this paper.