You are creating a model that shows how data moves through a system.

 Data flow diagramming is a technique that shows how data moves through a system, from external entities, through processes, to data stores. Data flow diagrams can be used to model the current state or the desired state of a system, and to identify gaps or redundancies in data processing. Data flow diagrams can also be decomposed to lower levels of detail to show the sub-processes and data elements involved in each function. Functional decomposition, work decomposition, and organization modeling are different techniques that can be used to break down a system, a project, or an organization into smaller components, but they do not focus on the data movement. References:

BABOK® Guide, p. 10, 98-99

CBAP / CCBA Certified Business Analysis Study Guide, p. 240-241

Certified Business Analysis Professional™ (CBAP®) | Coursera, Course 2, Week 2, Video: “Data Flow Diagrams”