An
association is denoted by a solid line between two blocks.
Associations in the domain knowledge model are normally not directed,
i.e., they have no arrowheads or, in SysML/UML lingo, no navigation direction.
From the domain ??™ s perspective, either direction is both present and meaningful.
For example, not only the customer as the booking party belongs to usage right ,
but also a usage right. Associations are denoted with role names ( booker , right )
and multiplicities ( Figure 2.66 ).
Figure 2.67 shows the domain knowledge model of the on-board computer.
The abbreviation bdd in the diagram header stands for ??? block defi nition diagram. ???
The associations are read in the following pattern: ??? A block has multiplicity
block in the role specifi ed by role name . ??? This sentence must be meaningful
for the domain. Let ??™ s test it in a simple example: ??? A customer has null to one usage
right in the role right. ??? Though this sounds a bit clumsy it makes sense.
What makes sense and what doesn ??™ t will be decided by your principal or the
domain experts in cases of doubt.
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