Number of matched DEM objects according to the most important comment by Davies et al. (1976): Diffuse shells or envelopes, nondiffuse or filamentary shells or envelopes, non-shell filaments or arcs, diffuse, complex, and uncommented. Objects with several comments are listed as shells if “shell” is mentioned and as filaments if “filament” but not “shell” is mentioned. The uncommented objects appear to be shell- or envelope-like or are filamentary in our images.