For those who have reached this level, congratulations! You're now officially part of the Disco-Tron 3000's inner circle. Proceed to Level 5 if you're ready for more secrets.
Or, you might be interested in the Level 3 Access Only area. It's a real blast from the past.
Don't even think about trying to access this level without Level 4 clearance, or you'll be terminated (and possibly forced to watch an endless loop of Stayin' Alive).