You can create an Atomic State on a State Diagram or through a Modeler browser. Define an Atomic State's incoming and outgoing Transitions on a State Diagram.
To create an atomic state on a state diagram:
1. On the State Diagram toolbar, click the Atomic State button.
2. On the State Diagram, click in free space or within a Sequential State.
3. Type the name of the Atomic State, and then press the Enter key.
To create an atomic state in a Modeler browser:
1. Right-click the State Machine or Sequential State that is to own the Atomic State, point to New, and then click Atomic State.
2. Type the name of the Atomic State, and then press the Enter key.
Atomic State button.