@hamogu. Well it's not quite a temporary solution.I was involved in the API shaping of some of the wcs part of @nden 's model framework so I know that the things I have written here are not really duplicating the @nden's work. I think not much will change in this specwcs - but will be greatly enriched by actually inheriting from the astropy-`model`. One example is that we will get an easy way to fit these models - so we can ditch IRAF for the wavelength calibration part pretty much right away ;-)