I expect it is because of https://news.ycombinator.com/item?id=8113410 https://news.ycombinator.com/item?id=8113410 (Medieval Manuscripts online). This article

I expect it is because of https://news.ycombinator.com/item?id=8113410 https://news.ycombinator.com/item?id=8113410 (Medieval Manuscripts online). This article exposed folks to the images of the manuscripts, which use the abbreviations.