Object
+--Exception
+--NoMemoryError
+--ScriptError
| +--LoadError
| +--NotImplementedError
| +--SyntaxError
+--SecurityError # Was a StandardError in 1.8
+--SignalException
| +--Interrupt
+--SystemExit
+--SystemStackError # Was a StandardError in 1.8
+--StandardError
+--ArgumentError
+--FiberError # New in 1.9
+--IOError
| +--EOFError
+--IndexError
| +--KeyError # New in 1.9
| +--StopIteration # New in 1.9
+--LocalJumpError
+--NameError
| +--NoMethodError
+--RangeError
| +--FloatDomainError
+--RegexpError
+--RuntimeError
+--SystemCallError
+--ThreadError
+--TypeError
+--ZeroDivisionError