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, or with a hertz separation.
A “logical string” can be represented by up to 7 “virtual strings”. How many virtual strings are created is set by tapping the appropriate number in the segmented control. It makes more sense to have large numbers of strings in a course when you don’t have a lot of strings anyway.
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 setting 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.
The Hertz setting separates the strings by that Hertz value, which means you can have a constant beat in yuor string pairs (or more). A single string will be offset by this amount plus or minus on alternating strings. This makes for a very subtle effect!