rework the exception hierarchy; refs #8363

doc/exception_hierarchy_fragment.txt

@@ -1,28 +0,0 @@
-* `Exception <system.html#Exception>`_
-  * `AccessViolationError <system.html#AccessViolationError>`_
-  * `ArithmeticError <system.html#ArithmeticError>`_
-    * `DivByZeroError <system.html#DivByZeroError>`_
-    * `OverflowError <system.html#OverflowError>`_
-  * `AssertionError <system.html#AssertionError>`_
-  * `DeadThreadError <system.html#DeadThreadError>`_
-  * `FloatingPointError <system.html#FloatingPointError>`_
-    * `FloatDivByZeroError <system.html#FloatDivByZeroError>`_
-    * `FloatInexactError <system.html#FloatInexactError>`_
-    * `FloatInvalidOpError <system.html#FloatInvalidOpError>`_
-    * `FloatOverflowError <system.html#FloatOverflowError>`_
-    * `FloatUnderflowError <system.html#FloatUnderflowError>`_
-  * `FieldError <system.html#FieldError>`_
-  * `IndexError <system.html#IndexError>`_
-  * `ObjectAssignmentError <system.html#ObjectAssignmentError>`_
-  * `ObjectConversionError <system.html#ObjectConversionError>`_
-  * `ValueError <system.html#ValueError>`_
-    * `KeyError <system.html#KeyError>`_
-  * `ReraiseError <system.html#ReraiseError>`_
-  * `RangeError <system.html#RangeError>`_
-  * `OutOfMemoryError <system.html#OutOfMemoryError>`_
-  * `ResourceExhaustedError <system.html#ResourceExhaustedError>`_
-  * `StackOverflowError <system.html#StackOverflowError>`_
-  * `SystemError <system.html#SystemError>`_
-    * `IOError <system.html#IOError>`_
-    * `OSError <system.html#OSError>`_
-      * `LibraryError <system.html#LibraryError>`_

doc/manual.rst

@@ -3968,9 +3968,12 @@ exception.
 Exception hierarchy
 -------------------
 
-The exception tree is defined in the `system <system.html>`_ module:
-
-.. include:: exception_hierarchy_fragment.txt
+The exception tree is defined in the `system <system.html>`_ module.
+Every exception inherits from ``system.Exception``. Exceptions that indicate
+programming bugs inherit from ``system.Defect`` (which is a subtype of ``Exception``)
+and are stricly speaking not catchable as they can also be mapped to an operation
+that terminates the whole process. Exceptions that indicate any other runtime error
+that can be caught inherit from ``system.Error`` (which is a subtype of ``Exception``).
 
 
 Imported exceptions