Absorption spectroscopy and line properties for GRB 210610B. Top: Spectral features detected at the redshift of the GRB, plotted in red, and the features from the intervening system are shown in blue. The dashed blue line shows the error spectrum. Bottom: Line-strength diagram for the spectral features in the host galaxy. The diagram compares the features measured in our spectrum (red) with the average values of a larger sample (black) (see Sect. 3.3).