Segments is a CV signal generator. You set start and end CV levels, and the amount of time you want the output signal to take to get from the start level to the end level, then hit the trigger to start the segment. Along with the CV signal it emits a gate signal for a controllable percentage of the time the segment is playing (so you can leave time at the end for an ADSR to release), and an end trigger when it comes to the end of the segment.
One of four selectable curves (linear, quarter sine, inverse quarter cosine and sinusoid) can be applied to the generated segment. The start and end levels can be modulated, either in "sample and hold" mode where the levels are fixed when the trigger fires and remain fixed until the segment has completed, or in "continuous" mode where the start and end levels, and hence the intermediate values, can change while the segment is running.
Instances of Segments can be chained to build up longer sequences, with each segment being triggered by the end trigger of the previous segment. CV signals can be passed through along a chain of segments, with each instance either emitting its signal if it is playing or passing through the input signal if it is not. A segment or chain of segments can be looped so that plays forever.
Segments is not intended as an audio-rate waveform generator - because the length of each segment is set in a whole number of samples, it loses pitch accuracy at higher frequencies. (It can be quite fun to trigger it with an audio-rate waveform, however). It is good as an envelope generator for long-running and non-standard envelope curves, a frequency CV source for electronic drums (kicks and blips), and a read-head position control for Catkins (the purpose for which it was originally developed).