Question for all you nymphers out there.....

When the general rule is that you place the indicator 1.5 to 2 times the depth of the water, what is the reference point for that measurement.

Is it 1.5 to 2 times :

above where you put your weight ?
above where your first fly is on a two nymph set-up ?
above the dropper fly(bottom fly) ?

The more I am out fishing and reading, the more questions that I keep asking myself.

Everyone's thoughts are appreciated......