Add more layers than what's displayed in the UI?

bpy.context.scene.layers contains 20 items.

Is it possible to add more?
bpy.context.scene.layers.append(something) doesn’t work of course. Is there a way to append item or it is locked?

It doesn’t look like it
in
http://www.blender.org/documentation/blender_python_api_2_71_release/bpy.types.Scene.html?highlight=layers#bpy.types.Scene.layers

layers
Visible layers - Shift-Click to select multiple layers

[TABLE=“class: docutils field-list”]
[TR=“class: field-odd field”]
[TH=“class: field-name”]Type:[/TH]
boolean array of 20 items, default (False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False)
[/TR]
[/TABLE]

The amount of layers is hardcoded to 20. You could set up a custom layer system however, I believe there are even addons for this already.

Just use more scenes. You get 20 layers per scene.

I saw some addon for doing that but if it doesn’t use Blender’s layers but its own system, it should means that render layers are not be compatible because their relationship is broken. That’s why I asked to extend layers number.

That’s what I do for the moment with link objects. It works but I find it less easy to work with when new objects are created, etc.

Thanks for your answer