Finish-to-StartWith a finish-to-start (FS) and zero lag, the successor activitycan start immediately after or later than the predecessor activityfinishes, so that the earliest possible start time of the successor isthe next day of the predecessor’s EFT. For example, as shown inFig. 2, Activity A finishes at the end of Day 3, thus its successorswith FS:0 can start at the beginning of Day 4 or later. SinceActivity B belongs to Calendar 2, it cannot start on Day 4. ActivityB can start at the beginning of Day 8, which is the nextavailable working day on Calendar 2.With a FS and positive lag, the successor can start at the lagtime after or later than the predecessor finishes, so that the earliestpossible start time of the successor is the next day of the predecessor’sEFT plus the amount of lag time counted by workingdays on the predecessor’s calendar. For example, as shown in Fig.3~a!, Activity A finishes at the end of Day 3, thus its successors with FS:1 can start at the beginning of Day 5 or later. SinceActivity B belongs to Calendar 2, it cannot start on Day 5. ActivityB can start at the beginning of Day 8, which is the nextavailable working day on Calendar 2.If the lag is 3 days as shown in Fig. 3~b!, it will be counted onCalendar 1 and the earliest possible start time of Activity B is Day9. Since Day 9 is a working day on Calendar 2, Activity A canstart at that time.With a FS and negative lag, the successor can start at the lagtime before or later than the predecessor finishes, so that the earliestpossible start time of the successor is the next day of thepredecessor’s EFT less the amount of lag time counted by workingdays on the predecessor’s calendar. In other words, the successorcan start when the remaining duration of the predecessoron the predecessor’s calendar is at most the lag time. For example,as shown in Fig. 4, Activity A finishes at the end of Day 3,thus its successors with FS:−1 can start at the beginning of Day 3or later. Since Day 3 is a working day in Calendar 2, Activity Bcan start at that time.