Weighted Curve Fitting

In the Igor manual (Chapter III8), it says:

"If the trace you are fitting has error bars and the data for the error bars come from a wave, Quick Fit will use the wave as a weighting wave for the fit. Note that this assumes your error bars represent one standard deviation."

Will Igor use standard deviations as weights? Or will Igor use the inverse variances as weight--as is commonly done in weighted fitting?

Also in the detailed curve fitting menu, it has two options for weighting: standard deviation and 1/standard deviation. Will Igor automatically convert the standard deviation to variance for fitting?

Thank you,
Geoffrey