|Office Developer Reference|
expression An expression that returns a IRibbonExtensibility object.
|bstrRibbonID||Required||String||The ID for the RibbonX UI. For Word, Excel, PowerPoint, and Access, there is only one ID for each application. For Outlook, there will be one for each type of Inspector object.|
In the following example, written in C#, the IRibbonExtensibility interface is specified in the class definition. The example then implements the interfaces's only method, GetCustomUI. The method creates an instance of a SteamReader object that reads in the customization markup in an external XML file.