This is a special control for setting the distribution of strings in a course. Normally, a string is one string that is set to a determined frequency. You can make it so that a "string" is actually a set of strings, either randomly or equally spaced.
This "logical string" can be represented by up to 7 "virtual strings". How many virtual strings are created is set by tapping the numbers in the segmented control.
The intervallic range of the virtual strings' spacing is controlled by the slider and the triangle buttons. All ranges are truncated to a tenth of a cent. You can set the range up to an octave (1200.0 cents) which extends both "sharp" and "flat". The slider is nonlinear, giving more accuracy at low values. Each tap on the triangle adds or subtracts one tenth of a cent for fine tuning.
The random feature even extends to 1 string! That way you can make a PolyHarp with out of tune strings, as if it were left in an attic for a few years.