ListProperties and ListRelationships
ListRelationships: enable modelling 1-N relations, i.e. the relationship to a set of entities represented as an ordered array of entityIds [as opposed to many individual 1-1 relationships, which are modelled as multi-relationships (with datasetIds)] have one common set of meta data [as opposed to individual meta data for each relationships in the multi-relationships case] ListProperties: enable modelling an association to an ordered array of values