Claiming a Workstation
At 7 minutes to the half-hour (i.e. hh:23 and hh:53) the booking system starts a countdown process where it allocates workstations to the next slot's bookings and sends a series of warnings to logged in users who don't hold bookings. On the half-hour mark the current users are forcibly logged out and the workstations will then reject logins from anybody but the booked user for another 7 minutes. Both of these 7 minute periods are known as the grace period because they give the current user of the workstation enough time to gracefully finish their work and logout, and the booked user enough time to gracefully find the lab and login. Or so the theory goes.In practice users occasionally find they are delayed and do not reach the lab until after the 7 (really 14 in total) minutes have elapsed, only to find that the workstation has allowed somebody else to login. This does not mean the booking has been trashed and you'll have to wait until the next half-hour, however. Go to a bookterm, login and type claim. This notifies the booking system that you are ready to take up your booking and it starts the countdown process for the logged-in user. This means that you will have to wait several minutes to gain your booking if the logged-in user chooses to wait out the entire countdown; a mild punishment for being late.
Class Bookings
There are 2 types of class bookings: tutorial bookings where nobody other than a student enrolled in the booking class can login for the entire duration of the class booking, and laboratory bookings which are similar to private bookings in that students from other courses are allowed to login after the grace period elapses. A student from the booking class can, however, still claim a workstation as above.
Note that bookings made during the grace period will end up being allocated to the next-but-one booking slot, not the next one. So if you want a booking at 11:00, say, you will have to make it by 10:52.