Although not yet available on Apple’s download site, Mac OS 9.1’s Software Update control panel is notifying users that they ought to download the Authoring Support 1.1 extension.
The 1.5MB update adds support for new drives, and increases reliability for your CD burning apps like iTunes and Disc Burner, according to Apple. The software also includes a new version of Apple System Profiler that will tell whether a CD-RW drive is compatible with iTunes/DiscBurner.
The Authoring Support extension is necessary for “burning” CDs with iTunes.