Thank you for this! This app is brilliant. I've just spent about 30 minutes setting my clipboard to all sorts of things.
I see now that the missing value class gets stored on the clipboard as its 4-byte character code 'msng'. In fact, even the class «class » is still composed of four NUL characters and takes up space.
I did find out, however, that you can omit the direct parameter and do
set the clipboard to
which stores 0 bytes but still somehow has two pasteboard flavours associated with it. So it seems like the Objective-C method is the only way to get a truly clean, empty clipboard.