EN 16803-1 addresses the final stage of the performance management approach, i.e. the assessment of the whole Road ITS system performance equipped with a given Positioning System, using the Sensitivity analysis method. EN 16803-1 addresses the identification and the definition the positioning performance features and metrics required for Positioning System assessment. This document gives definitions of the various items to be considered when specifying an Operational scenario and provides a method to compare finely two environments with respect to their effects on GNSS positioning performance. This document gives definition of the most important terms used all along the document and describes the architecture of a Road ITS system based on GNSS as it is intended in this standard. This document does not address: the performance metrics to be used to define the Road ITS system performance requirements, highly depending on the use case and the will of the owner of the system; the performance requirements of the various kinds of Road ITS systems; the tests that are necessary to assess Positioning System performances (Record and Replay tests for this purpose will be addressed by prEN 16803-21 and prEN 16803-32).