11   Exceptions

This clause defines the facilities for dealing with errors or other exceptional situations that arise during program execution. An exception represents a kind of exceptional situation; an occurrence of such a situation (at run time) is called an exception occurrence. To raise an exception is to abandon normal program execution so as to draw attention to the fact that the corresponding situation has arisen. Performing some actions in response to the arising of an exception is called handling the exception. 

An exception_declaration declares a name for an exception. An exception can be raised explicitly (for example, by a raise_statement) or implicitly (for example, by the failure of a language-defined check). When an exception arises, control can be transferred to a user-provided exception_handler at the end of a handled_sequence_of_statements, or it can be propagated to a dynamically enclosing execution.