Control Bone Shape Conventions

Sorry, its my first real face rig and I’m realizing there is a huge amount I don’t know.

What are the generally expected shapes for control bones when rigging a face?
I have seen it posted before but can’t find it.

I think it was like “square” shapes for location controls
“???” for controls with rotation
“???” for scalable controls
Are there standard shapes for combinations like controls with location and rotation?

If there is a guide or standard you could point me to that would be great also.

Thanks in advance

If I understand what you are asking, you can give any Custom Shape to the bone display you like. How to assign custom shape is show at the end of this tutorial:

Thanks for the tut. I appreciate it.
I thought I has seen that there were general shapes to help the animator know how a bone could be posed.
For instance, if the shape was basically a squarish shape, it was meant to be translated in X,Y, Z but not rotated or scaled.
Maybe my old brain just thinks I saw this.
I was wanting the shapes I used to be more intuitive for the animator.

fwiw you can’t go wrong by studying the BBB and Sintel rigs!