Transform Flow

In the fundamental system model level zero data flow diagram information must exit and enter software in an external   world   form example for, tones on a telephone line, data typed on a keyboard and pictures on a computer graphics display are all forms of external world data.  Such externalized data must be converted into an internal form for processing. The time history of data can be described in figure 20.1. The Information enters the system along paths which transform external data into an internal form and will be identified as incoming flow.  The kernel of the software a transition happens. Incoming data are passed by a transform begin and enter to move along paths which now lead out of the software. The Data moving along these paths are called out going flow.  The whole flow of data occurs in a sequential follows and manner one or only a few straight line paths.  When a part of a data flow diagram exhibits these characteristics transform flow is present.