A Signal Boundary Event can receive a Signal. In this context, it will change a normal flow into an exception flow upon being triggered.
A Signal Event differs from an Error Event because it defines a more general, non-error condition for interrupting Activities, such as the successful completion of another Activity, and it has a larger scope than the Error Event does.
Signal Boundary Event displays either of the following on a diagram:
A Signal Boundary Event name if the name is specified.
A Signal Ref property value if the name is unspecified.