Early day. Answer
Gary Smyth
Dust panel is the answer. Gold star for your forehead.
I selected this trivia because I went looking for furniture searching for a particular maker and ran into a sales person who ought to have known better but had never heard of a dust panel. Apparently some of the "moderate" and upwards furniture manufacturers have determined that they are no longer of value. I noticed that if the furniture has an internal frame, often there is a routed groove on the inside of the frame, but the dust panel is absent. Perhaps the groove is there to make a crossmember tongue easy to place anywhere necessary. I'm wondering if this is not only because of cost but that some manufacturers have simply let the purpose lapse owing to the fact that furniture is no longer a priority to a younger demographic. I'm getting testy. I appreciate well made anything, but for the crowd younger, the things that matter most seems to be new, more, and obsolete. With the soft close drawer metal runners, lost will be the joy of the whisper sucking in of air when a correctly fitted drawer is opened, or the push back of air when it is compressed when shutting it. 