QoX: What is it really?

The article puts in order notions related to Quality of Service that are found in documents on service requirements. Apart from presenting a detailed description of QoS itself, it overviews classes of service (CoS) proposed by main standardization bodies and maps them across various transmission technologies. Standards and concepts related to less commonly used, though not less important, terms such as Grade of Service (GoS), Quality of Resilience (QoR), and Quality of Experience (QoE) are also discussed. While provisioning of QoS, CoS, GoS, and QoR is related to various aspects of networking and network performance, QoE describes resulting service features as perceived by the customer. Relations between those intrinsic network features and resulting human-experienced quality are discussed. The above set of QoX terms (where X stands for Service, Experience, etc.) is sufficient to describe and distinguish all aspects of service provisioning.