8Data Flow Diagrams Symbols
There are some symbols that are used in the drawing of business process diagrams (data flow diagrams). These are now explained, together with the rules that apply to them.
Flow diagrams in general are usually designed using simple symbols such as a rectangle, an oval or a circle depicting a processes, data stored or an external entity, and arrows are generally used to depict the data flow from one step to another.
A DFD usually comprises of four components. These four components can be represented by four simple symbols. These symbols can be explained in detail as follows: External entities (source/destination of data) are represented by squares; Processes (input-processing-output) are represented by rectangles with rounded corners; Data Flows (physical or electronic data) are referred to by arrows; and finally, Data Stores (physical or electronic like XML files) are presented by open-ended rectangles.

Data flow diagrams present the logical flow of information through a system in graphical or pictorial form. Data flow diagrams have only four symbols, which makes it useful for communication between analysts and users. Data flow diagrams (DFDs) show the data used and provided by processes within a system. DFDs make use of four basic symbols.
Create structured analysis, information flow, process-oriented, data-oriented, and data process diagrams as well as data flowcharts.
External Entity
An external entity is a source or destination of a data flow which is outside the area of study. Only those entities which originate or receive data are represented on a business process diagram. The symbol used is an oval containing a meaningful and unique identifier.
Process
A process shows a transformation or manipulation of data flows within the system. The symbol used is a rectangular box which contains 3 descriptive elements:
Firstly an