A short reply is that I am not aware of any format requirements.
A long reply is that I’ve seen a very detailed guidance regarding CTD (Common Technical Document) data table formats years ago but have not been able to find that or any other specific guidance in recent years. In a past work environment, I searched high and low for guidance on data table formats. I even assigned it as an annual goal for one of my direct reports to search for anything anywhere, and they didn’t find anything. The guidance I’d seen years before must’ve been a draft guidance and maybe it was withdrawn, because we could not find it or anything like it out there. This was important to us because we’d spent a lot of hassle keeping to what we’ve thought was the required CTD format and would like to have gotten away from it if allowed.