looking at these expressive dirt bands
dirt bands in library card catalogs, similar to dirt and wear marks on the fore edges of books gives some evidence of use
this can be useful research, but it has silently disappeared over time due to lack of archiving materials like card catalogs
some of these issues also pop up with digitizing physical books and throwing them away... we lose the information about how they were bound, how they might have been used, all the physicality is gone