Colour-colour diagram of IR WISE counterparts of X-ray sources in the field of CMa OD (left). The region of different types of sources are shown based on the study of Wright et al. (2010). Colour–magnitude diagram of Gaia counterparts of the X-ray sources in the field of CMa OD (right). The background sources, Galactic foreground sources, stellar objects, and candidate members of CMa OD, plus their candidates are shown in different colours and symbols. Colour red indicates Galactic foreground stars and stellar systems, orange show foreground object candidates. Classified background sources are shown in blue and the candidates in light blue. Sources in green are stellar objects and light green are stellar object candidates. The symbiotic candidates are shown in purple. The sources without classification are shown in black. Moreover, the known sources with entries in SIMBAD are shown with crosses and sources, which are classified through this work are marked with circles. Stellar objects that are considered members of CMa OD are shown with filled squares.