The functions you use to connect to ActiveX servers accept a class ID (CLSID) as a parameter as an alternative to a programmatic identifier (ProgID) so that you can connect to servers that do not have a ProgID. All ActiveX servers are required to have a CLSID.
ConnectToObject, ConnectToNewObject, ConnectToRemoteObject, and ConnectToNewRemoteObject all accept either a ProgID or a CLSID for the classname argument.
The following ConnectToNewObject calls are equivalent. The first uses the ProgID for Microsoft Word 97; the second uses its CLSID: