Layered topic map
Layered topic map -- also called a layer stack -- is a special topic map construct that combines multiple separate topic maps into a single topic map. You may think a layer stack as a folder that merges all including topic maps. Typically layer stacks are used to collect dependent topic maps under a single label. Layer stacks can build up a nested folder structure i.e layer stack can contain layer stacks.
In order to write into a layer stack, the stack must contain at least one real topic map implementation, a memory topic map for example.
See also Introduction to Layered Topic Maps.
Creating new layer stack
To create new layer stack select Layer > New layer and select layer type Layered. You also need to name the layer stack. After layer stack creation you can move other layers into the layer stack or create new layers in the stack.
Below is a screenshot of Wandora's layer structure after layer stack creation. After stack creation Wandora user has created two new layers within the stack. New layers are called New layer name and another layer. Both new layers are memory topic maps.