Trimpot adjustment range

[Tj138waterboy]

After combing through the forum I am still unable to see how to find a formula to calculate how much trim range you get with resistor divider. I stumbled upon article for building voltage reference for home lab and found the selected trim values odd being much higher than datasheet examples for ref102 voltage reference. The writer uses 3.6meg in line with 100k trimpot. Can anyone point me in the right direction to see why such high values are being used an or how much range this setup has? Schematic is on pg 11.

[mvs]

Trimpot is used to supply 0-10V at wiper. Its resistance is quite low at end positions and does not really matter.
If you look at internal schematic of REF102 in the datasheet, you will find internal resistor values.

Trim range with 3.6M resistor should be around +/-29mV. You can approximate it with 5*(1-(x+50K)/(x+72K)), where x is 3.6M resistor.