[NTG-context] Referring to multiple elements

Hi, how can I refer to multiple elements at the same time? \starttext \startplacefigure [title=foo, reference=alpha] \stopplacefigure \startplacefigure [title=bar, reference=beta] \stopplacefigure \startplacefigure [title=bar, reference=gamma] \stopplacefigure \in{figure}[alpha,beta,gamma] \stoptext This outputs “figure 1”. What I'd like to have is “figure 1-3”. Marco