What Are Tools Used in Process Modeling? Process modeling, sometimes called structured analysis and design, is an analysis and design technique that describes processes that transform inputs into outputs. Tools used for process modeling include the following. An entity-relationship diagram (ERD) graphically shows the connections among entities in a system. An entity is an object in the system that has data. A data flow diagram (DFD) graphically shows the flow of data in a system. Key elements of a DFD are a data flow, which shows the input or output of data or information; a process, which transforms an input data flow into an output data flow; a data store, which is a holding place for data and information; and a source, which identifies an entity outside the scope of the system. The project dictionary, sometimes called the repository, contains all the documentation and deliverables of a project. Techniques used to enter items in the project dictionary include structured English, a decision table and/or a decision tree, and a data dictionary.