In contrast to RDF collections (rdf:List), they have a stable identity and don't use nested resources (=easy to remove). Furthermore, standard RDFS inferencing can be used to infer membership as the property rdfs:member.
Yet, most RDF vocabularies that I know of use collections and syntaxes such as Turtle have syntactic sugar for collections, but not for containers. Why is that? Axel -- axel.rauschma...@ifi.lmu.de http://www.pst.ifi.lmu.de/~rauschma/