The sources for the notation are often the same as for the actual concepts. In
cases where the domain is related, for example, to user interfaces, the notation can
be de?¬?ned rather easily, as was done in the mobile application case presented in
Chapter 8. Also, if the domain to be modeled includes physical structures or has
already established representational forms, the de?¬?nition of the notation is
considerably easier. You may use symbols of the physical product, such as a valve
or sensor, to denote the actual software behind these concrete product elements.
Usually all notational elements cannot be fully derived from already known symbols,
so the rest must be created for languages. However, there is no reason to create new
notation just for the sake of having something new. Instead, you should use and borrow
good representations already in common use. Use the base language and model of
computation you started with to help and guide you. For example, in models
describing behavior such as state machines, ?¬‚ow diagrams, activity diagrams, and so
on, well-established notation for start and end states already exists: a dot and a circle
containing a dot. If your language gives additional semantics (modeling concepts or
their properties) for the start and stop states, you may well extend the representation.
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