Just occurred to me some of you may not know about the tracking strips in American money. I checked a five dollar bill earlier, and it had the strip in it.

Look at the bill face-on. Lincoln looking back at you. On inch in from the left, start a small tear at the top of the bill and tear down and to the right. Gotta be a hand-made tear, not scissors, because scissors will cut the metal. Tear about a quarter inch down and to the right, and you'll encounter resistance. Pull the paper apart carefully until you see the shiny bit under the light. That is a metal strip which runs from the top edge to the bottom edge of the bill. Woven into the linen. You can hook it and pull it out even. A magnetized thread. It was in the five I just did, and it's in other currencies, but I forget which. Those 'anti-theft' devices at store doorways can tell how much money you have in your pocket. If you enter with no money, you might be a shop lifter. If you exit with a package but have the same amount of cash as when you entered, you might be a shop lifter. That's 1990 technology, too.