@User Yes, measured capacitances are provided as function of line width and space, with and without top and/or bottom plate in underlying and overlying metal layer. For resistance the same is done as a function of line width; I am not sure but maybe even some short length effects may be included in the latter. This is what I and @User refer to when talking about capacitance tables. One problem is that sometime foundries provide this data encrypted.

@Aled Cuda, @FatsieFS: The Calibre QRC decks provided by SkyWater seem to be pretty complete. I used those to derive the simpler approximations for magic, and earlier today ran a test layout through Calibre and Magic and got approximately the same parasitics (within a percent or so). The layouts were designed to not have the kinds of geometries that cause the approximations to become inaccurate. But the Calibre deck has equations for fringe capacitance that would appear to capture the common nonlinearities.

Have these been published yet?

What exactly can replace Calibre for signoff?