What is the relationship between an OBJECT tag’s CLSID and CODEBASE attributes?
It is possible to specify any CLSID paired with any CODEBASE in an OBJECT tag. If that CLSID isn’t already registered, IE will attempt to download the control specified in the CODEBASE attribute of the OBJECT tag. It isn’t feasible for IE to know what control a package installs before that package is actually installed.