Gaia DR2: For now, Gaia DR2 data are not in SIMBAD, it is available in Vizier. The CDS will perform a cross-identification of Gaia DR2 with the astronomical objects in the SIMBAD bibliographic database. This will be done with very strict criteria in order to avoid erroneous cross-identifications. Especially, only the 6.5 milllions objects with subarseconds coordinates will be searched in Gaia DR2. Expected to be ready on June 30, 2018.
(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases