[Inkscape-user] Perfect Bound Cover Template.

The Perfect bound template is found under Extensions==>Render. One of the parameters is for cover thickness. Do I enter the thickness for one side or for both?

For example 360 Digital Books asks for a cover thickness allowance of .038 inch. It is clear from the context that this is for both front and back covers. In Inkscape should I enter .038 in or .019 in?