A 'breakpoint' conversion is a complex set of calculations in which different equations are applied to input voltages depending on where they lie in relation to a specified 'breakpoint' voltage.  For example, you might apply a linear conversion to all data of <2 volts, but a polynomial conversion for values >= 2 volts.  This window lets you set the breakpoint conversion conditions:

Each breakpoint conversion operation involves up to three different equations, each of which can be linear, exponential, 2-order polynomial, or power.  The initial conversion is (optionally) applied to all data regardless of voltage. The other two 'secondary' conversions are (optionally) applied to data above or below breakpoint, respectively.  The secondary conversion can either be added to or multiplied by the results of the initial conversion (this is selected with the 'operator' buttons) and can use either raw voltages or the values from the initial conversion (selected with the 'apply to' buttons).  Note that the breakpoint itself is always specified as a raw input voltage.

The window shows a summary table of the three equations at the bottom. You enter the coeffients in the three edit fields at top center, and then click the appropriate button to enter them into the initial or secondary conversions.  The 'get x' and 'store as x' buttons let you save and retrieve up to 6 complete breakpoint conversions in memory.  To save them more permanently in a preferences file, click the 'store values' button or use the 'store preferences' option in the FILE menu.  If you save them in a file called "LabHelper prefs" and it is located in the same folder as the LabHelper program, it will be loaded automatically at startup.