If you even have to ask, you pretty much have to conclude it doesn't exist. The biggest complicating factor probably comes from the metadata requirement, which is difficult to standardize (both in what gets reported either by necessity or optionally, and in what format each data type takes). I'd say the most common de facto standard (on Unix systems, at least) for verification is what gets generated by the various `*sum` utilities (and also optionally by `openssl`) that gives a hash and filepath. Anything beyond that, you might be best served by trying to co-opt some standard archiving tool's format (e.g, `.tar` or `.zip`) using [sparse files](https://en.wikipedia.org/wiki/Sparse_file) or a dummy compression algorithm to represent the metadata without storing the file data itself. Otherwise, I think all you can really do to keep things portable is to pick a generic, easily parsed format like CSV/TSV or YML/JSON or XML, and just fill in the blanks with the specific information you need to move around. Push comes to shove, you write a converter that reformats that into some vendor's pet format. I'm going to need exactly this sort of thing for a project I'm working on, and I've pretty much decided to go with a TSV format if I stick with text files. If I find there's any strong need to go beyond that, I'm going to use a [SQLite](https://sqlite.org/index.html) database. 5eb9151a284a89c3d9921e0f606ecb0cc42deb880527c969de9504ddcc798502