local layers how to ?

Support Basics & Interface
1

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?

thanks

2

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

3

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

thanks