The layers of a region can be interspersed freely with single layers, groups, and layers of other regions. You can use this property in combination with the
change color action to define complex alterations of icon appearance.The members of a region are included in the region by the fact that they have the same region name. Region names are arbitrary symbols: a region exists as soon as you name it as the region of one or more layers. A layer's region name (if any) appears at the bottom of each layer in the region. It also appears in the Region Indicator when the layer is selected.
To add a layer to a region:
none if the layer does not belong to a region.