I believe it means that it is listed for use in something else that was previously listed to contain only certain things.
For example, CH breakers classified to install in Siemens panelboards.
I remember seeing Nora can trims classified for use in Halo and Capri cans.
The can had certain specific trims that were listed for use in that housing (all of the same brand, for instance Capri trims for a Capri can), and only those trims or a competing trim classified for use in that housing (such as the Nora trims) could be used.