Nomenclature of multiple systems based on the resolution of Gaia DR3 (blue circles) and 2MASS (orange circles). From left to right: ‘A+B’ (resolved in both surveys), ‘AB’ (only resolved in Gaia), ‘(AB)’ (not resolved either in Gaia or 2MASS, but resolved by adaptive optics, lucky imaging, or space imaging), and ‘Aab’ (spectroscopic binaries). Multiple systems can often be a combination of these cases.