I've been burnt by filesystems when moving around between external drives and FTP, so while I'd strongly prefer if there was a universally accepted way to include arbitrary metadata in the file itself, I'm instead using a separate metadata file. My metadata files are named exactly the same as the original, including their original extension, with a ".metadata" appended, to minimize confusion, and use INI/TOML format to maximize the chances that I'll be able to understand and find tools to easily parse the files after several decades.
I've been burnt by filesystems when moving around between external drives and FTP, so while I'd strongly prefer if there was a universally accepted way to include arbitrary metadata in the file itself, I'm instead using a separate metadata file. My metadata files are named exactly the same as the original, including their original extension, with a ".metadata" appended, to minimize confusion, and use INI/TOML format to maximize the chances that I'll be able to understand and find tools to easily parse the files after several decades.