Layer Operations: Clear, Delete, Edit Specification

Three full-layer operations are implemented which are available in the "Layers" submenu of the "Edit" menu:

• Clear: clear but don't delete the currently active layer in the layer list.
• Delete: clear and delete the currently active layer in the layer list.
• Copy: Copy the contents of a layer to another layer.
• Edit Layer Specification: edit the layer specification of the currently active layer in the layer list.

The "layer specification" describes how a layer is saved to GDS or OASIS streams. It consists of a layer and datatype number and optionally - for OASIS - a layer name.