In mathematics a variable can be said to be constrained if it must lie within certain bounds, for example:
0 < x < 1 (the variable x is constrained: it lies between zero and one)
However some kinds of variables (such as an angle, or time of day) can be constrained with an additional property that their values form a closed loop: if I increase the value past the upper bound it reappears at the lower bound. For example:
11 o'clock + 2hours = 1 o'clock
Is there an adjective or name to describe this kind of 'circular' variable?