This concert had one of the few real encores I have ever experienced.
The Allman Brothers were the headliners on a three act bill (Cheech and Chong was one of the other performers). The Allman Brothers came on late. By the time they finished their first set, they hit the TCC curfew. The lights were turned on in the arena. The crowd kept cheering for more. The Allman Brothers came out and played Mountain Jam, past the curfew. The TCC would not turn out the lights, so the band played on, with the lights blaring.
Most encores are planned and obligatory. In this case, the band played on due to the audience’s enthusiasm. It is rare, and I have only seen it few times (once with PFM in a bar-ChooChoo’s). When Yes hit the curfew at the TCC, they stopped playing.