## Scheduler

### Slots volatility

A reuseable slot will remain in the scheduler even a student or the teacher revokes an appointment. The freed slot is available again for appointing.

A volatile slot will be automatically deleted in the above cases if it has to start to close to the current dat (it is considered you may not want to add a constraint so close to "right now"). The guard delay can be set by the instance-scoped configuration parameter "Reuse guard time".