When a user passes the pointer over the name of a user on a SharePoint site, a function named EnsureIMNControl is called, which is defined in the file OWS.JS. This function creates the NameCtrl control on the page as follows:

new ActiveXObject("Name.NameCtrl.1")

OWS.JS is located in the Local_Drive:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\LAYOUTS\1033 directory on each front-end Web server in a Windows SharePoint Services deployment.

A developer can create a custom control for displaying presence information if it has the same ProgID (Name.NameCtrl.1), uses the same method or property names, and provides the same functionality that is described in this reference. Functions can be created that handle the event in which the online status of a specified person changes.

When the 2007 Microsoft Office system is installed on the client computer, the NameCtrl control is defined in the NAME.DLL file, a dynamic-link library that is installed on the client during 2007 Office system setup in the Local_Drive:\Program Files\Microsoft Office\OFFICE12 directory.