Astropy has emerged as an integration of several independent packages (PyFits, asciitable), each responsible for an individual task in the storage, reduction and analysis pipeline of the astronomical data sets. It has mostly unified the interface in order to make these entities coalesce. However, the need for Astropy to shine as a single package and not just a collection of functionally independent modules, calls for seamless interoperability between the three special and powerful constituents of Astropy: coordinates, time and units and the underlying Astropy table writers. We seek to develop a protocol that allows their storage, the mixin columns, in FITS and ASCII ECSV, while still ensuring "round-tripping". Abiding by the rules set by the FITS standard, requires mapping of the special Astropy objects, with extensive associated metadata, to the standard keywords. We thus want to achieve the ideal goal of preserving complete information, while still going hand in hand with the defined standard.