DR (Default Role)
DR stands for Default Role. It is an additional refinement on which staff should be used to populate the shift. With this checked, only staff that have the fill from role set as their default role. So only the staff who primarily work in this role can be assigned the shift, rather than any staff member with the role assigned.
When disabled, the system will use any staff member with the fill from role assigned.
This also has an additional mode which is shown as a green tick with a plus (). In this mode, the schedule tool will assign to default role members first. If none are available then it will expand to include all members of that role.