+from collections import namedtuple
+
+exc_types = ['alignment',
+ 'instr_fault', # this one is not an actual exception
+ # but information *about* the type of
+ # exception that must be generated
+ 'invalid',
+ 'badtree',
+ 'perm_error',
+ 'rc_error',
+ 'segment_fault',
+ 'happened', # must be last: may overlap with Data.ok
+ ]
+
+LDSTExceptionTuple = namedtuple("LDSTExceptionTuple", exc_types)