"The present document serves as a collection of requirements and use-cases of the different stakeholders along the value-chain for the ECI Ecosystem as specified in the ECI multi-part deliverable@ including specification of the architecture of the ECI system as defined in ECI specification ETSI GS ECI 001-1 (V1.2.1) [1]. An ECI Ecosystem which fulfils these requirements will reveal the following features: A major advantage and innovation of the ECI Ecosystem@ compared with currently deployed systems@ is a complete software-based architecture for the loading and exchange of CA/DRM systems@ avoiding any detachable hardware modules. Software containers provide a secure (""Sandbox"") environment for either CA or DRM kernels@ hereafter named as ECI Clients@ together with their individual Virtual Machine instances. The Advanced Security System is a powerful tool for the ECI Client to enhance its security. The download process is embedded in a secure and trusted environment@ providing a trust hierarchy for installation and exchange of ECI Host and ECI Clients and thus enabling an efficient protection against integrity- and substitution attacks. The present document covers requirements details in the following clauses: Clause 4 contains all requirements structured in clauses: 4.1 Generic Requirements; 4.2 Versatility related Requirements; 4.3 Practicability related Requirements; 4.4 ECI Client Swap related Requirements; 4.5 ECI System Security related Requirements; and 4.6 Content protection and Usage Rights Information (URI) related requirements. Annex A deals with relevant use cases."