Raising an exception reports an error, not by returning a value, but by propagating an exception. Propagation involves searching all active scopes for code written to handle the error or code written to perform scope-completion actions in case of any error, and then causing that code to execute. If a scope does not define a handler or epilogue block, then the scope is simply torn down as the exception propagates through the stack. This is sometimes referred to as unwinding the stack. DCE Threads exceptions are terminating; there is no option to make execution resume at the point of the error. (Execution resumes at the point where the exception was caught.)
If an exception is unhandled, the entire application process is terminated. Aborting the process, rather than just the faulting thread, provides clean termination at the point of error. This prevents the disappearance of the faulting thread from causing problems at some later point.
An example of raising an exception is as follows:
RAISE (parity_error);