This document provides a Concept of Operations (CONOPS) for the introduction and maintenance of a Mixed Vendor Environment (MVE) in the domain of urban-ITS. Structured as: PART I Context and issues to be addressed Describes the context, background, objective of the MVE Guide, and describes the architectural context. PART II work concepts Aspects of system design and architecture are examined and the basic knowledge required for the application of Part III are presented. PART III Practice Provides system design and procurement on three levels against the background of a procedure model. user level; conceptual explanation; examples. PART IV Outlook Guidance and requirements for the application of MVE for future business.