Link Clusters and Calendar linked 2D calendar+clusters shows patterns plot: number of employees vs. time of day office hours, fridays/summer, school break, weekend/holidays, post-holiday, santa claus [van Wijk and van Selow, Cluster and Calendar based Visualization of Time Series Data, InfoVis99, Figure 4, citeseer.nj.nec.com/vanwijk99cluster.html] 29