raises an exception of extype n rounded to an integer, where n is a numeric expression.
Available exception numbers are from 1 to 999 (reserved for users) and pre-defined extypes.

If a CAUSE EXCEPTION statement is executed in an exception handler, an exception shall be raised again. If a when-body includes the when-block that the exception handler belongs to, the control branches to the exception handler related to the when-block. Otherwise if no when-body includes the when-block, when the CAUSE EXCEPTION statement is located in a procedure, the exception shall be propagated to the invoking statement.