  The development of new assessment methods for the performance of automated
vehicles is essential to enable the deployment of automated driving
technologies, due to the complex operational domain of automated vehicles. One
contributing method is scenario-based assessment in which test cases are
derived from real-world road traffic scenarios obtained from driving data.
Given the complexity of the reality that is being modeled in these scenarios,
it is a challenge to define a structure for capturing these scenarios. An
intensional definition that provides a set of characteristics that are deemed
to be both necessary and sufficient to qualify as a scenario assures that the
scenarios constructed are both complete and intercomparable.
  In this article, we develop a comprehensive and operable definition of the
notion of scenario while considering existing definitions in the literature.
This is achieved by proposing an object-oriented framework in which scenarios
and their building blocks are defined as classes of objects having attributes,
methods, and relationships with other objects. The object-oriented approach
promotes clarity, modularity, reusability, and encapsulation of the objects. We
provide definitions and justifications of each of the terms. Furthermore, the
framework is used to translate the terms in a coding language that is publicly
available.
