This is a website that you can register your dollar bill and it will be tracked from location to location because the serial numbers are electronically scanned also (they match the metal strip).
This could be considered a TYPE of mark OF THE WORLD SYSTEM. The mark of THE BEAST (I consider the massive, monstrous "world system" a "BEASTly affront to the way of God on this earth), in human terms, may be more metaphorical and allegorical than we have been taught to think (we have been taught to think in LITERAL terminology). Only when a "mark" is forced to be applied to the FOREHEAD or RIGHT HAND will it have spiritual consequences (because The Lord specifically warned against it and disobedience will now be tantamount to rejection of God).
Radio Frequency ID is now known to be applied as a visble sticker on CD's and other products, but nanotechnology is now trying to make it a "SPRAY". If and when that is developed, we may not even be aware that it has been applied, but as long as we don't wiilingly accept it on our forehead or right hand, we will not express rejection of God and there can be no spiritual consequences (the electronic signals may drive us mad and cause us to do "irregular things" as in "shellshock"), but will have no SPIRITUAL effect on a "Godlover".
RFID tags are being attached to clothes in the factory/store, and unless you have removed them, you can be tracked. If you used your credit card to buy them, you are probably in a dozen databases for junk mail, etc.