The initial state is a pseudostate (see Section 20.11, “ Pseudostate ”) representing a source for a single transition to the default state of a composite state. It is the state from which any initial transition is made.

As a consequence it is not permissible to have incoming transitions. ArgoUML will not let you create such transitions, and if you import a model that has such transitions, a critic will complain.

There can be at most one initial pseudostate in a composite state, which must have (at most) one outgoing transition.

An initial state is represented on the diagram as a solid disc.