If you are developing a custom Ribbon for SharePoint 2010 you will need to look this file up at some time due to the fact that this file contains the Location and Group IDs for Ribbon Tabs. Eventually you can reuse lot of stuff if you need to. VS 2010 provides you intellisense but you can also use the Visual Studio Extensibility project for Ribbon Referred below.
Install the Server Ribbon Extensibility Project. VIA MSDN Blogs
Download the Extensibility project from here:http://code.msdn.microsoft.com/vsixforsp. Extract the contents and double click on the Server Ribbon.vsix file to install the extension. You can verify the extension is installed from the Extension Manager.
2. Add a new Server Ribbon Project Item
From a new or existing SharePoint project, add a new Server Ribbon project item from the new project item dialog.
Next Step 🙂 You already know. Dont???? ha ha F5