A doodle can have different layers containing any of the four drawing elements. A layer may also contain as many other layers as are approved by its owner.
The 'main' layer: the default layer shown at the inital viewing of a doodle.
can contain other users' layers by approval by owner, which can be done when the layer is submitted by its creator or beforehand.
Any other users' layers on top (including the owner).
Layer names are unique. By convention, users can name layers for:
Metadata (tags, notes, comments, related links)
Appropriation (additions, alternatives, replies, remixes, remediations, graffiti, defacement, etc.)
Templates. Any user can duplicate any layer from any doodle in his network into his own doodle.
This means a template creator can offer a template layer for anyone to use, which is a list of as many other layers of layout and metadata for users to appropriate and customize, such as:
Since the name of the original template layer is preserved when a user appropriates it, viewers can easily search for all doodles containing derivatives of a certain template. This will make it easy to find active games of exquisite corpse, for instance, or to search for all blogs by a certain user or clique.