[Zope] Selection properties - how?

[Itamar]

I want to add a Selection property to an object.  What format to I write
the multiple values in - I must be doing something wrong, cause every
time I try to make a selection property I get the following error:

Traceback (innermost last):
  File /itamar/Zope-2.0.1-linux2-x86/lib/python/ZPublisher/Publish.py,
line 214, in publish_module
  File /itamar/Zope-2.0.1-linux2-x86/lib/python/ZPublisher/Publish.py,
line 179, in publish
  File /itamar/Zope-2.0.1-linux2-x86/lib/python/Zope/__init__.py, line
201, in zpublisher_exception_hook
    (Object: ElementWithAttributes)
  File /itamar/Zope-2.0.1-linux2-x86/lib/python/ZPublisher/Publish.py,
line 165, in publish
  File /itamar/Zope-2.0.1-linux2-x86/lib/python/ZPublisher/mapply.py,
line 160, in mapply
    (Object: manage_addProperty)
  File /itamar/Zope-2.0.1-linux2-x86/lib/python/ZPublisher/Publish.py,
line 102, in call_object
    (Object: manage_addProperty)
  File /itamar/Zope-2.0.1-linux2-x86/lib/python/OFS/PropertyManager.py,
line 274, in manage_addProperty
    (Object: ElementWithAttributes)
  File /itamar/Zope-2.0.1-linux2-x86/lib/python/App/special_dtml.py,
line 120, in __call__
    (Object: manage_propertiesForm)
    (Info: /itamar/Zope-2.0.1-linux2-x86/lib/python/OFS/properties.dtml)
  File
/itamar/Zope-2.0.1-linux2-x86/lib/python/DocumentTemplate/DT_String.py,
line 502, in __call__
    (Object: manage_propertiesForm)
  File
/itamar/Zope-2.0.1-linux2-x86/lib/python/DocumentTemplate/DT_In.py, line
691, in renderwob
    (Object: propertyMap)
  File
/itamar/Zope-2.0.1-linux2-x86/lib/python/DocumentTemplate/DT_Util.py,
line 321, in eval
    (Object: _.has_key(select_variable))
  File <string>, line 0, in ?
NameError: (see above)