Figure 2. Illustrations of time related notations.

The network at the top illustrates that the panel below concerns one link. Panel a shows a time line of the contacts between two individuals in a link. The time between the start of the sampling and the first contact is the beginning interval t_B; the time from the last contact to the end of the sampling is the end interval t_E. Uppercase variable names refer to the time of event, while lowercase refer to the duration of intervals.