Reddening values E(B–V) and their given uncertainties taken from FPB16’s statistical distance compilation¹² plotted against Gaia BP – RP colours for all matches with reliability > 0.8 (not limited by parallax uncertainties). Known and suspected binary systems taken from the compilation of David Jones¹³ are highlighted as black squares¹⁴. Objects lying below the trend (objects appearing red in Gaia with low reddening) could be binary systems or have significant reddening internal to the nebula, or could have dubious identification. Relevant individual objects mentioned in the text are shown in red.