This tool is used to produce complex drawing output.
When an object is assigned to a layer the layer properties can be controlled making all objects on a layer either unselectable or invisible (or both). This allows you to work on parts of the schematic without accidentally selecting parts that are finished (by placing those parts on a separate layer).
The layers dialog also allows assignment of selected objects to the specified layer.
There are four columns and as many rows as specified in the options control box (see below).
The first column sets the current drawing layer that new items will
be drawn on (after exiting from this dialog). The second column
sets the visibility of items on each layer (when set the items are
visible and when unset the items are invisible). The third column
sets whether items on a layer can be selected (when set they can be
selected and when unset they can not be selected). The fourth
layer can be used to annotate the layer as a reminder of the layers
purpose.
If any items in the schematic are selected pressing 'Selection to
layer' will puts those items on the the current drawing layer.
Note : when grouping objects - they are grouped across selectable
layers - this means that dragging an object works as expected i.e.
objects on all layers are dragged.
This is useful for multi layer objects e.g. a library symbol on
layer 1 and its highlight on layer 2. If these are both selected
and grouped (see the grouping tool)
both of these will be dragged around the schematic together keeping the
symbol and its highlight together. If later on the highlight
layer is made unselectable the grouped symbol and highlight will still
both be selected as the grouped object overrides the layer.
The number of layers can be set from Menu: Edit --> Options
--> Schematic --> Max layers.