You are welcome to read the entire article (in fact, I hope you do), but in short, this new classification defines all the lenses you might mount on your camera in four tiers: new, current, legacy and outré. Let me briefly describe these categories:
• New lenses are those which are in production.
• Current are all those lenses which (while not new) are natively mountable and supported on bodies which are in current production.
• Legacy are all those photographic lenses which cannot natively be mounted on any new body without the use of an adapter.
• Finally, outré are all those optical lenses which never were designed for use as interchangeable lenses for a camera