You have two hot legs and one high leg (Power leg, wild leg, or stinger). And one neutral. I prefer power leg. If I were to change out your service, the first thing I would do is check rotation at the service entrance with a phase sequence indicator and write it in the panel. Marking the position of the hot legs with an H and the power leg with a P and a CW for clock wise or a CCW for counter-clock wise. Also the date and my initials. I would check it again after I changed out the service, before I told the customer he could close his main.
If you have an Open Delta bank, you have true 3 phase. This connection is relatively inefficient where three-phase loads predominate since it has only 86.6% of the rating of the two units making up the three-phase bank. It also has only 57.7% of the three-phase rating of a closed delta bank of three units.
Don