I am doing an ac sim at one frequency using a design variable
as the swept parameter. How do I refer to this design variable (what syntax) in the ADE calculator so I can use it in a plot equation

Thanks Pancho:
Using VAR("variable_name") only plots the static
value the variable is set to in ADE. I am using this variable as the
sweep value in an ac sim.
Ex. I have a variable gain cell whose gain is controlled with a control
     current "Igain" I do an AC sim at 100Hz using Igain as the sweep
     variable. I can plot the cell gain (which is vs. Igain in the
     waveform window). I also want to plot this gain minus a multiple
     of the sweep variable Igain to access the linearity of the gain char.
     vs Igain but I don't know what to call the sweep variable Igain
     in the calculator.