# Working with Packets

## Chapter 2. Working with Packets

## The Packet Tree

A single Regina data file can store a rich variety of objects, from 3-manifold triangulations and normal surfaces to Python scripts, PDF documents and text notes. All of these objects are called packets, and are arranged in a tree-like structure as you can see below.

To view or edit a packet, just click on the packet in the tree (on some platforms, such as MacOS X, you need to double-click instead). The packet will open up in a new window, as shown below.

### Uneditable Packets

Sometimes you will find that Regina does not let you make changes to a packet. This typically means that the packet is constrained by its children.

For example, if a triangulation has normal surfaces or angle structures beneath it, then Regina will not let you change the triangulation because this would invalidate the normal coordinates or angle structure coordinates.

Uneditable packets such as this will be marked with a small padlock in the tree: see the Figure 8 Knot Complement in the illustration below.

If you find yourself in such a situation, you can always clone the packet. This will create a new copy of the packet without any children, and you will be able to edit your clone instead.