Since large documents can have many footnotes it can be difficult to keep track of which ids have been used. To make it easier to come up with unique ids for every footnote in a single large document, I use a date and time format. For example, the footnote id [^202505291403] corresponds to May 29, 2025 at 14:03. It’s unlikely I’ll reference two things in the space of a minute, this ensures that each footnote id is unique and easy to reference.