[Zope] Missing "how to"s

hi all, I am looking for the documentation of the "multiple selection" type, but the "how to" does not exist anymore on zope.org..... argh... Has anyone of u a copy of the documentation? If it is the case, please send me, or explain me how does it work.... (what I want is a ZClass propertie wich allow to choose an item in a list, I though multiple-selections were fine for that). Thanks for your attention. Pierre