Can I extend NSFileProviderItemCapabilities to create my own capability?

I am using NSFileProviderItemCapabilities to manage functionality available to a user. One feature is whether the user can download a file or not. NSFileProviderItemCapabilities does not have this capability supported out-of-the-box.

I created the following

extension NSFileProviderItemCapabilities
{
    public static var allowsDownloading: NSFileProviderItemCapabilities {
        // All NSFileProviderItemCapabilities raw values go up in powers of 2 (expect allowsAll which is 63)
        return NSFileProviderItemCapabilities(rawValue: 62)
    }
}

var capabilities = Capabilities()
capabilities.insert(.allowsDownloading)

Using this custom capability results in the following being stored in the capabilities variable.

No allowsDownloading is present and other NSFileProviderItemCapabilities have been added.

Playing around, if I were to reduce the rawValue of allowsDownloading to 2, it adds the following capabilities.

Is extending NSFileProviderItemCapabilities not possible or am I doing something wrong?