Document Icons Schema
The Document Icons Schema is used in the DocIcon.xml file to map file name extensions and ProgIDs to associated icons, and to controls for opening each file type. DocIcon.xml is located in
\\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\XML.
For a programming task that describes how to customize this file, see How to: Add a Document Template, File Type, and Editing Application to a Site Definition.