[Zope] property/selection/value

Hi, there is this option for a folder to add some properties with standard types, like boolean, date etc. Is there a way for (multiple) selection not only to define the displayed text for each popup-entry, but also the "value" for the generated option-tag or the "name" of the select-tag? Where do these defined properties live within zope, and how can I access and manipulate them directly? Andreas