Table 3.

Definitions of use case diagram and usage scenario.

Definition		Example
Use case diagram
	Unified Modeling Language provides use case diagrams in order to specify and describe use cases. These are cases of the system (ie, a description of how the user interacts with the system). Use cases are generally organized in steps, which can be considered smaller usage components (and therefore can be described as discrete use cases).	An example of use case is the selection of a drug and/or an adverse reaction upon interaction with a form displayed by the system. Another use case is to read posts from social media for this selection.
Usage scenario
	Usage scenarios are circumstances in which a user will interact with the system. Multiple usage scenarios can be defined that can correspond to a single use case.	Making a pharmacovigilance survey is a usage scenario. Indeed, we can decompose the survey into smaller components to look for similar case reports in the national pharmacovigilance database, make a literature search, and perform a search in social media.