The ETSI MANO Model operational stack is defined as Orchestration above Network Function Management above Infrastructure Management. The ETSI MANO Model is a framework that defines the architecture and interfaces for the management and orchestration of network functions virtualization (NFV) in cloud networks1. The ETSI MANO Model consists of three main components: Infrastructure Management, Network Function Management, and Orchestration2. Infrastructure Management is responsible for managing the physical and virtual resources that host the network functions, such as servers, storage, switches, hypervisors, andvirtual machines2. Network Function Management is responsible for managing the configuration, monitoring, and optimization of the network functions, such as scaling, healing, and updating2. Orchestration is responsible for coordinating the allocation and release of resources for network services and network slices, such as instantiation, termination, and modification2. The ETSI MANO Model operational stack is defined as Orchestration above Network Function Management above Infrastructure Management, meaning that Orchestration is the highest level of abstraction and control, Network Function Management is the intermediate level, and Infrastructure Management is the lowest level2. References: 1: Nokia Bell Labs Distributed Cloud Networks, Unit 5: New Services Automation, Section 5.3: Orchestration 2: Module by Module - Self Study Note Guide - training2