What is a common attribute of both UML activity diagrams and Structured English, in terms of task documentation?

The focus on defining the flow of control makes this the correct choice. Both UML activity diagrams and Structured English serve to illustrate how processes or workflows proceed from one step to the next. In UML activity diagrams, this flow is represented through various symbols and arrows indicating the sequence of actions, decisions, and concurrent flows. Structured English, on the other hand, uses a textual format to describe conditional logic and sequential steps, detailing how the control moves between tasks.

By concentrating on the flow of control, these methodologies help in ensuring clarity when documenting processes, making it easier for stakeholders to understand how various tasks are interconnected and how the process unfolds over time. This attribute is essential for effective process modeling, allowing for both visual and textual representations of the control flow within business processes.

The other options mention characteristics that, while they may apply to one or the other, do not equally define the core attribute shared by both methodologies. For instance, reserved words are specific to Structured English, and visual representation is characteristic of UML activity diagrams specifically. Text-based formats are not a feature of UML diagrams at all, as they rely primarily on graphical elements. Therefore, the focus on the flow of control is the commonality that ties both methods together.