Comment view level - hide from end user.
I tested the Add Comment function in 7.5 sp1 and realized it doesn’t work the same way as in 7.1.x.
After reading this article I see it is by design:
We use the Public/Private view levels extensively in 7.1.x. We use this to inform colleagues of proposed solutions, information or opinions that we do not want the end user to see. The end user see the Public view level comments and the private comments is visible to all the members of our support organization.
I can't imagine that we are the only organization that needs to add information in tickets that end user does not need to see. I would be very interested in how others have solved this.