At the end of a shift there may be a reduction in the number of Resources available. If some or all of the Resources that are removed are currently engaged in work at Activities then the behavior tab describes what happens.
Behave as if the Resource was still at the Activity (or stays on late after the end of the shift) and complete the task in hand - then don't start another. Vehicles always complete their task before Resources are released at shift end. Note: this option will be unavailable if one of your Activities is Shift Dependent.
Suspend but restart ASAP
Stop the work and hold the Activity in suspension until another Resource can be found (perhaps because one finishes work at another Activity).
Suspend until next shift change
As above but don't let any remaining Resources be used on suspended Activities. Suspended Activities should not be considered for restart until the next shift change.
The behavior tab also lets you control what happens when shifts overlap. The default is that Resources that are available in two shifts that overlap are available to the extent of the largest availability of the two shifts. You can change this assumption to summing together the two availabilities.