Attachments are shown as icons where they are attached. These icons are the same icons as those used in File Manager and other places in the Common Desktop Environment. The basic rule of behavior is that if the same icon is used in File Manager as in an attachment, then every effort should be made to make the two behave the same in every situation.
There are three levels of functionality for attached documents:
Ability to attach and detach documents
Ability to open, view, and quit an attached document in a separate window
Ability to edit the attachment in a separate window and save changes back to the attached document
The goal is to provide Level 3 functionality whenever possible. If an attachment cannot provide this level, then it should degrade its level of functionality in the steps shown. This section is written assuming Level 3 functionality.
If a document provides significantly different functionality as an attachment from that provided as a File Manager icon, then provide a different icon for the attachment to clearly indicate to the user the difference in functionality.