Should missing coated side assume no coating ("neither") or be an error?

[StephenCzarnecki]

So far coated side is only used for calculating hemispheric emissivity for products that have measured wavelength values in the range specified by the THERMAL IR method of the optical standard being used for the calculations. However since the source for this data can potentially be created by users it is possible to create something that has wavelength data but is missing the coated side.

How should this be treated in WinCalc? I think the options are either assume that neither side is coated or throw an error in the thermal emissivity calculations.

[jcjonsson]

I think it makes the most sense that it throws an error.