On the V4S Roster add-on, you may sometimes see an indicator that shows 0 vols.  This indicator means that no Volunteer or Teacher has Checked in yet for today's class (Shift).

0 Vols indicator on RosterAssume that your Student check-in is being handled separately at a front-desk or gate. This indicator is a good way for the person doing the student check-ins to know that the Teacher/Volunteer has not yet checked in. So if there are young children that are being checked in, the person doing the check-ins can make alternate arrangements for adult supervision, until the Teacher handling the class checks in. 

The 0 Vols indicator remains on the screen until the Teacher/Volunteer checks-in for the class. The 0 Vols indicator automatically disappears once the Teacher/Volunteer has checked in.