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42 Data flow diagrams 
4.2.1 Task areas 
The DFD shows a clear division between “voyage planning” (Process 1) and executing or monitoring the 
voyage (Process 2). The “current voyage plan” memory represents the connecting link between these 
two processes. Amongst other things, this memory contains the set track valid in the system, which is 
usable for automatic track control. Further processes are used for the procurement and administration 
of data (mainly irrespective of the current course of the voyage: Process 3 (integrated in the voyage 
progression: Process 5). Process 3 - “Management of data and reference parameters” - models the 
“Sea chart management’ (i.e. the administration of the geographical data base for voyage planning and 
execution) and the recording and administration of ship data. The data flow “State variables” forming 
part of Process 3 primarily models the transmission of the ship's position for selection of the current sea 
chart. 
It should be borne in mind that the whole “integrated navigation” process chiefly supplies two items of 
output information: “Set rudder angle" and “Set engine data”. The information flow via the current val 
ues of rudder angle and engine data is effected via the process “State identification” and is thus encap 
sulated in the data flow “Sensor data”.