flags

Very strange. Only correlation I can see is I upgraded to Monterey on Friday. So, the new rabbit hole, is suddenly the email has gone wonky. Smart Boxes don't work, and clicking from box to box, shows same number of emails available (let's say 8000) no matter what I click on. Then, I discovered...

I'm looking for an iconset set I saw recently (I thought on xicons.com) but I can't find it anymore. The set contains of a lot of aqua flags exactly like the one below:

how can flags be added to an executable, ex. ls -a