For each Principle of the Recommendation, suggestions of pitfalls to avoid and potential solutions are also provided. For each component of the Recommendation, the checklist suggests key self-assessment questions for countries to evaluate their own state-of-play and areas for improvement in order to prioritise their implementation efforts. The methodology for key performance indicators is currently under revision in line with the OECD Recommendation of the Council on Public Procurement (2015). They cover in detail three principles on stakeholder engagement, regulatory impact assessment and ex post evaluation, and provide a baseline measurement to track countries' progress over time and identify areas for reform. The indicators are expected to be updated every three to four years.