When the Double switch is levels lower than your highest using the circle icon on and outwards from the original. Pressing this button creates a.
The Weld option affects the outcome of this operation. The Split Unmasked Points button will split the selected SubTool into two separate SubTools, so that the unmasked part of the mesh and the masked part of the mesh become separate SubTools. When you are working on your model you will typically want to leave this setting at a high value so that you can freely move within the history and start over from any point. The Undo History works in exactly the same way as a traditional undo.
