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2.6.3
DFD Context
One of the DFD types that is going to be used in this thesis is the Context Diagram
(DFD Context). Wilkinson et al. (2000, p. 122) define it as the top level of a set of
logical
DFDs, since
the
process
in encompassed
within a single circle.
According
to Romney and Steinbart (2006, p.
66), it provides the reader with
the summary-
level view of a system; it depicts a data processing system and the external entities
that are the sources and destinations of the system’s inputs and outputs. A system’s
scope and boundaries are illustrated by this type of DFD.
2.6.4
DFD Level-zero
Another
type of
DFD that
is
going to be applied in the analytical process of this
thesis is the Level-zero Diagram (DFD Level-zero). It is called the level-zero DFD
because of the zeros following the decimal points; this level just below the context
diagram (Wilkinson
et
al.
2000,
p.
123).
It
"expands"
the single
process
on
the
context diagram to show the major, high-level processes (or functions) within the
system. All external agents (sources and sinks) are included because the level-zero
diagram, like the context diagram, represents the entire system.
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