Question about enrollment appointment

Hello, experts!

I have the following concerns in relation to the enrollment appointment. When I do the assignment of appointment for students appears day initial, end date, start time, and end time, but I see that the student can enrollment a different block defined in the appointment date or without enrollment appointment.

My question is, the enrollment appointment is only for informing students? or the system can to control that only the student assignment in the appointment block can enrollment?

Regards,

Jean Carlos