The Z.350-Series Recommendations provide a specification technique for the human-machine interface. This interface is known as the G- interface of the Telecommunications management network functional architecture. The scope of the G-interface is defined to include the human readable specification of the common terminology and grammar and of each external presentation, as well as the external presentations themselves. See Recommendation Z.352. The centralization of a common terminology and grammar ensures a harmonized human-machine interface across every external presentation. The Z.350-Series Recommendations are provided to resolve problems which are encountered when using the specification technique recommended in Recommendations Z.331 to Z.333. The main deficiency was lack of means to provide consistent and precise definitions of all the data encountered at the human-machine interface (HMI). The Z.350-Series Recommendations supersedes the specification technique provided in Recommendations Z.331 to Z.333 and should be used for all future development of specifications. This new specification technique is expected to provide a powerful framework for the development of future HMIs.