### Incompatibilities

On the other hand, CG02 section 6.1.4 stress that the AIPS convention cannot represent oblique celestial coordinate graticules such as the one shown in [their] Fig. 2. CRVALi for these projections [(AIT/Aitoff, GLS/radio, MER)] in AIPS does not correspond to the celestial coordinates of the reference point, as understood in this formalism, unless they are both zero in which case no translation is required. In other words, these 3 projections do not fit into the CG02 general formalism (unless the reference point is on the Equator). See next subsections for details.