I use the Calibre ebook viewer to read (reflowed) pdfs and happily take highlights, export etc.
However I'm wondering
where those annotations/highlights are actually being stored?
They reappear when I go in and out of previously edited pdfs, but are they attached to the Calibre app (the pdfs aren't in my library), are they embed in the pdf (other pdf readers can't see em), or what?
I'm opening the files from Zotero (with the ebook viewer as the default reader).
Thanks for your help and time,