A lot of people today are taking down walls in homes to give a more open feel or change the layout of rooms. As a result there is usually an outline of where the old existing wall has sat on the timber floors.
As you can see in the photos the mark from the wall in this case has been successfully sanded out and in the finished result you would not know the wall was ever there. You can also see how the boards have been rejuvenated in the before and after photos with the gloss polyurethane finish that was applied. These clients were very fortunate in the fact the outline of the wall was not visible after sanding as this is not always the outcome. In most cases you can still see an outline where walls have been removed.
The same applies to kitchen cabinetry when the footprint changes you can be left with markings/outlines of where old cabinetry use to sit. We never know until after sanding and coating if the marks have gone.