3) and
the term internal block diagram instead of composite structure diagram (as in
UML; Section 3.4).
Blocks describe a system as a collection of parts that each play a certain role
in a defi ned context. Look at this specifi c example: The construction plan of the
card reader block is described in the block defi nition diagram ( Figure 4.29 ) and
its role is described in the context of the on-board computer in an internal block
diagram of the on-board computer ( Figure 4.28 ).
4.5.1 Block
FIGURE 4-28
Card reader in the on-board computer.
4.5 Block Diagrams
ibd [block] On-board computer [access system]
:Card reader
:On-board
computer control
:Customer card
Defi nition
A block describes parts of the structure of a related system.
It is a stereotype ?«block?» of the UML element class.
Together with the block, SysML defi nes an element to be used for describing the
static structure of systems. A block can be both a logical and a physical unit (software,
hardware, functional blocks, and so on).
The notation deviates slightly from the standard representation of stereotyped
classes.
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