A hard constraint that ensures that the number of periods that are occupied by activities within a specified time block does not exceed a specified limit. The constraint is applied to every time block that is part of the constraint. For example, a constraint that limits lecturers' daily teaching time to four hours might consist of multiple time blocks, one for each day of the teaching week.
A time block can span multiple days, for example a whole week, and you can apply multiple constraints to an item. So, for example, you could additionally apply a maximum hours constraint that limits lecturers' teaching time for the week to sixteen hours.