Question on Replacement Path parameters

I am creating a formula variable. with Replacement Path. On the Replacement Path tab in the Replacement Rule section, I do not understand the parameter settings. For example, for 'Replace Variable With', I have the choice of 'InfoObject' or 'Variable'. Can you explain each of these choices?

Also, explain the choices in the 'Use Interval' section (ie, From Value, To Value, Difference).

Thanks.

Ron