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I amnot 100% sure of the abbreviation LNSF or INSF. The lower case is ambiguous to my eye.
When I look at the form in total, I am leaning toward a meaning of Linear Scale Facor as a percentage of length and as a resulting distance calclated from it.
Again, interpreting this form, I believe the scale factor is a characteristic of the projection and your location within it.
I assume the previous replies are correct. Using an electronic total station - one may be invited to enter temperature, barometric pressure and relative humidity. When that is entered the display shows a scale factor for the EDM.
I believe the form is laid out in such a way that one figures the scale factor as a percentage. Then the user multiplies the raw length by the scale factor to determine the linear quantity result of applying the SF. The linear quantity is added to (or subtracted from) the raw quantity to determine the final, useful quantity.