The operational safety of intelligent vehicles (IV) is a central topic and a complex issue on which many research projects are focused. While there is no consensus yet on the most reliable way to validate driving automation systems, several methods exist such as scenario-based testing and real-time operational domain (OD) restriction based on the specification of the operational design domain (ODD). In our case, we focus on the role of the ODD concept as a safety guarantee for IVs and how, combined with real-time monitoring of their operational domain (OD) can act as a safeguard for complex mobile systems. We propose to analyze the related literature, standards, works and proposals made in the field of OD/ODD monitoring for operational safety and to assemble them into 3 categories : the first concerns the use of taxonomies and ontologies to represent the elements of the vehicle driving environment ; the second concerns the formal definition of the ODD through a dedicated language ; the third concerns techniques allowing the monitoring of the vehicles' OD to improve operational safety. By taking a step back from the identified methods, we highlight how they can be combined in a coherent manner, to progress towards a framework enabling ODD definition and OD/ODD monitoring.