Prop is one of the microlanguaged embedded inside of Sporth. It is a rhythmic notation system based on proportions.
Prop can be used to create very complex drum machines and rhythmic profiles.
In Sporth, there are two ugens for prop. prop is the original ugen that compiles a prop string and a BPM, and creates a set of ticks. The ugen called tprop is identical to prop, except that it has a trigger argument that resets prop to the beginning.
For a full explanation of prop, consult the prop project page.