ALLEGRO generated a reference document, addresses technical requirements of next-generation optical networks, definition of use cases and detailed KPIs, an architecture definition and a preliminary demo execution plan. In the context of use cases, a range of general scenarios for next-generation services, along with specific cases to validate various technologies, were defined. KPIs and technical requirements were identified for these scenarios. The general use cases encompass services with significant requirements such as high bandwidth or strict constraints on latency, availability, or reliability. Specific use cases cover 6G Ready Optical Transport, Security Plane, SDN, and Sustainability scenarios. In line with the project objectives, relevant KPIs, use cases, and planned devices, initial hardware and network requirements have been outlined. This includes specifications for transceivers (with SOA amplifier), optical switches, and QKD technologies. Additionally, the document addresses network KPIs, mapping them from the original proposal objectives to network-level implications and open issues. The document also showed the reference topologies that will be used during the project and the methodology that will be used to generate the traffic matrices. Additional synthetic topologies can also be generated to provide additional insights for the techno-economic studies that will be carried out. The proposal incorporates an architecture that outlines both a short/mid-term (evolutionary) and a long-term (disruptive) ALLEGRO architecture. The description covers the data plane, the control plane, and the traversal security plane, presenting the enabling technologies and solutions for each of them. A table has been included to align the network-defined KPIs and objectives with the selected solutions in the proposed architecture. The document also includes an initial plan for the demonstrators, describing their locations and a preliminary list of participating partners.