Looks like it does -- no supplementals for me and the total number of pages goes down, too. But the site: command has been so flakey that I wonder what these many hack-type site: queries I read about actually return.
Still, thanks for the tip. It's an interesting new toy to play with.
One challenge that I have with these undocumented operator queries is this:
The supplementals-only query above gives me urls that also show in the regular search results without a supplemental tag. They even have the same cache date in both incarnations. In fact, some other site: operator queries also show the same url/cache date without the supplemental tag.
So what action can I sanely take on this basis? My concern is that these queries are tricking the site: operator into a worse-than-usual level of accuracy by asking them to perform outside the way they were designed.