With the release of Final Cut Pro 10.6 Apple introduced a new XML format. The original FCP XML was known as fcpxml and was a single text file, as is all XML. The new format – fcpxmld – is a package, not a single file known as a Bundle. A ‘Bundle’ in macOS appears as a single file in the Finder, but is a special type of folder that is read as a single file. Most apps are packages. The FCP Library is a Bundle.