With this option derivated outlines can be locked in the drawing, ie. with a change of the original objects (move, rotate, delete, etc.) the usually attached outline will not be re-adjusted with the object.
The work with this option is helpful when outlines are definitively not be changed, like boundaries of a construction site. Or when outlines are supposed to be set invisible (see Control of visibility) or simply the relevant layer is deactivated. This way, you can be sure that masses once detected will not get changed. A check can be done with the designated option.
Start the command Lock with Menu Extras > Outlines > Lock
With locking the outlines the option Check outlines will also be activated for outline-objects in the tab Properties.
The changes only apply to the current group and its contents, but not to any other outline-objects in the drawing. If all outlines are supposed to be locked in the drawing the fuction has to be applied on the level of the group All.