If you display when 3 dimensions vary, you get an animation sequence. You can animate through any of the three varying dimensions.
By default, the animation dimension is time. You may set which dimension to animate through:
set loopdim x|y|z|t
If you wish to animate when fewer than three dimensions are varying (ie, animate a line graph), you can control animation by entering:
set looping on|off
Remember to turn looping off when you are done animating, or you will get suprised when you enter your next expression.