We’re just talking about the filename, the exact creation time is tracked by the OS. Plus I’d imagine most documents also have a time and date inside. The file name is mostly for sorting and human readability.

It’s just a filename, calm down. The created by date is tracked by the file system and the repo.

The exact date of creation is usually preserved in the filesystem, we’re just talking about what to name the documents themselves. The filename should be short and to the point, it gets truncated if it’s too long, and on windows you only have 260 characters for the entire path to the file plus the name.

Here you go gramps:

(shortD) => {
    return parseInt(shortD.slice(0, 2), 10) > 50 ? "19" + shortD : "20"+shortD;
}

ISO 8601 is YYYYMMDD (or YYYY-MM-DD in extended format)

Are you really going to wood chipper someone for leaving off the leading 20? I think we can safely infer the century and millennium with a high confidence, why not trade them for two extra name characters?