Chapter 3: HIERARCHY

## 3-8: Rearranging Hierarchy

### Creating New Levels of Hierarchy

In order to manipulate hierarchical circuits, it is useful to create and delete levels of the hierarchy. The Package into Cell... command of the Cells menu collects everything in the highlighted area into a new cell. You will be prompted for the cell name. The most convenient way to specify an area for packaging is to use the rectangle select button and drag a rectangle. Every node touching the area is included in the new cell. All arcs between nodes in the area are also included. The highlighted circuitry is not affected.

### Removing Levels of Hierarchy

The opposite function is the removal of levels of hierarchy. This is done with the Extract Cell Instance command, which takes the currently highlighted cell instances and replaces them with their contents. Repeated use of this command goes further down the hierarchy until it is fully instantiated. All arcs that were connected to the cell instances are reconnected to the correct parts of the instantiated circuitry.

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