Dominik Wujastyk's blog
My conjecture as to why the other one was rather low seems, however, to have been wrong. Apparently somewhere around here is this scribe's preferred height. Not sure how old the term kuṇḍala for such an abbreviation sign is; quite possibly not nearly as old as the use of the signs. Thanks for the reference to Patel's recent paper, which I haven't yet seen, in your comment on the other post.