Scope and reporting criteria NS bases its reporting on the Global Reporting Initiative (GRI) version 4 guidelines. The GRI guidelines are the most widely accepted guidelines worldwide for preparing non-financial annual reports. The guidelines themselves can be found at www.globalreporting.org. The sustainability information in the 2016 annual report has been given by NS in accordance with the Comprehensive option of the G4 GRI guidelines and internal reporting criteria.NS commissioned EY to provide the external assurance for the report. You can find the assurance report by EY on page 230 of this PDF. It contains an appraisal (with a reasonable degree of assurance) of a number of selected parameters and a conclusion (with a limited degree of assurance) regarding the chapters ‘The Profile of NS’, ‘Report by the Executive Board’, ‘Dialogue with our Stakeholders’, ‘Our Strategy’, ‘Finances in Brief’, ‘Scope and Reporting Criteria’, ‘Activities in the Netherlands’ and ‘Abellio’. NS feels that external assurance is important because it generates more certainty that the information given is accurate.Combined reportIn the NS 2016 annual report, the performance of NS, the social aspects of that performance and the financial results are presented as an integrated whole. This choice has been made deliberately. NS is at the heart of the community. Passenger transport by train and the commercial operation of stations and their surroundings are intrinsically important to society. Other social aspects, such as care for the natural and social environment, are thus also an integral component of the business operations of NSGRI indicatorsThe selection of the indicators is based on the GRI method, the Transport Plan 2016, the discussions with our stakeholders and the material relevance matrix derived from them. The information that we report is based where possible on measurements and calculations (e.g. for electricity consumption). Other data is taken from central administrative systems (e.g. HR data) or based on information provided by third parties (e.g. waste). If there have been changes in the definitions, measurement methods or the inherent limits in the data or if extrapolations or estimates have been used, this is specified in the report, the definition cards for the performance indicators in the Transport Plan, or the reporting criteria. The last two of these can be found on www.ns.nl/mvoberekeningen and the definition cards for the performance indicators in the Transport Plan 2016.Sustainability dataSustainability has been part of the regular planning and control cycle since 2010. This means that the data is reported in the monthly reports. The processes for collecting and validating the data are described in the CSR Handbook. The internal validation procedures are performed by our auditors. They examine deviations in the data with respect to previous reports, consider the plausibility of the data in the reports and request supporting evidence where necessary.ScopeThe scope of the report has been determined on the basis of an analysis of material relevance. This means that we are reporting on the materially relevant topics and drawing on the insights given by this analysis when making choices about the amount of detail and limits to our reporting on these topics. The material relevance matrix shows both the theme’s importance to stakeholders and the impact or influence NS has. Themes where NS has little impact or that are not seen as so important by stakeholders are not included in the report. Abellio was involved in the Dutch dialogue with stakeholders.The report covers the 2016 financial year, which ran from 1 January 2016 to 31 December 2016. This report primarily concerns NS’s activities in the Netherlands. The activities in the United Kingdom and Germany are also discussed where they involve operations in which NS holds a stake of more than 50%. All data has been measured unless stated otherwise in the methodology. Any estimates are carried out using the prescribed procedures from our Reporting Manual and then checked. An explanation of the margins of uncertainty in the data quantifying our impact can be found at www.ns.nl/mvoberekeningen (Dutch only). We report on the transport chain as a whole where procurement is concerned or where our process of value creation gives reason to do so. The choices we have made in this regard are specified under value creation. Where information covering the whole transport chain is reported, this is explicitly stated. Generally speaking, the report does not cover subcontractors or suppliers. In those parts of the report where this does occur, this is explained. Acquisitions are included in the data from the date of acquisition, disinvestments are listed until the date of disposal.