### The Hammer-Aitoff case

The Hammer-Aitoff projection (hereafter AIT) is similar to the GLS case, i.e. it is possible to convert from the old (AIPS) to the new (CG02) formalism by converting the projection description. But, while the GLS projection is known to have been used with non-zero declination reference (hence a new name for the projection), it is less obvious for AIT. Knowing that both AIPS-AIT and FITS-AIT formalisms are compatible at , CG02 have chosen to keep the same name for the new convention.