Defines the GUID (global unique identifier) for the extension.

<guid shortid="[name (string)]">GUID</guid>    

A GUID ensures that two different extensions with the same name are never in conflict. A GUID must be added before the first build of a binary extension and must never changed. When you update an extension, add features to an extension, or create a new version of the extension, never change the GUID.

Because ACT considers two extensions with the same GUID as the same extension, you can change the extension name in a new version of the extension without compromising compatibility with projects that were saved with the older version of the extension.

Attributes for the element <guid>