How do you query the index of FileMaker field using FileMaker Data API

[ggt667]

How do you query the index of a FileMaker field using FileMaker Data API?

The FileMaker equivalent would be to push ⌘ + I

I'm not asking how to achieve a sorted unique list of 10 000 000 records, I'm asking how to extract the n possible values from the index of the field in question. Where n probably is between 5 and 20. A poor man's solution to this is obviously using a value list; delivering the ideal values of the filed, but that's like positive testing and that will not deliver what I ask for.

Edited January 7, 2019 by ggt667