I'm very confused... I normally fly UA and have found them to be very clear about the boarding process and enforce it well.

However, I had 4 CO flights this weekend and found boarding on all 4 of them to be a disaster. On all 4 flights the gate agent asked for military and pre-boarding which seemed normal and fine. But then, they announced just First Class, GS, 1K, and Platinum. They did NOT say "Elite Access" or "Premier." I waited patiently assuming that they would call Star Gold next. But as more and more people kept on boarding I started glimpsing some boarding passes and saw lots of *S and 2P's boarding. Every 30 seconds the gate agent would announce "We're only boarding First, GS, 1K, and Platinum" as if she was seeing that lower elite levels were coming through, but she didn't stop any of them. Then, all of a sudden, she starts going through the general boarding process. I was upset because I had listened diligently and waited my turn but all Elites had boarded. There were a few other confused people too and we commiserated together.

This went on to happen on my next 3 flights as well. Agent only mentioned First, 1K, GS, and Platinum. Learning my lesson, I simply boarded then and had no problem.

My questions are, is there an official CO boarding process and why is it not being enforced or communicated clearly?