Your pivot point may end up outside of your final Bool. This button is simply a shortcut to Maya’s Modify > Center Pivot feature. Note - pivot points are left to a user’s discretion.
This toggle determines whether the Boolean types are set globally or on a per layer basis.
Set the boolean mode. Select from Union, Difference (Subtract) and Intersection. Depending on your Mode this icon may be greyed out.
Set the visibility of your objects. Select from Shaded, Wireframe or Hidden. Note - hiding an object will also hide it in the Outliner and vice versa.
Toggle whether a layer should be included in the calculation or not.
When on, Bool will identify any problems with the boolean and fix them by merging the vertices. It will also show you where the problem lies with a small yellow dot allowing you to resolve the issue and disable debug (and so optimise performance).
Layer order is important!
The top layer is considered the ‘master’ mesh. When the Mode is set to Global all the layers below the master are treated as if they were one combined mesh. When the Mode is set to Per Layer think about each layer as a sequential boolean operation. i.e. the top layer is calculated first, then the one below, then the one below that. You can reorder layers including swapping the ‘master’ layer for another. As long as your object is a mesh, Bool should accept it. Tip - that includes MASH’s ReproMesh.