local layers how to ?

right beside the layers on bottom header
there is a button for local layers

what does it do?
when is it usefull to use this?

is there any other indication when it is activated apart of this button icon?


If button is off the layer controls are local to that 3d viewport. You can then have multiple viewport windows showing different layers

seems to be a little bit more i guess
cause you cannot add duplivert if in local mode too!

but what else does it affect