On Tue, Jul 12, 2016 at 10:45 AM, Abu Dhabi <xxxxxx@gmail.com> wrote:
>>Most likely it is done with TL15 technowizardry. Every note is its own
>> encrypted computer system and will tell if it is genuine in about half a
>> dozen ways if prompted the right way.
>
> You might run it that way IYTU - might even work, and would certainly make
> more sense. In the OTU, the notes are just bits of plastic with a serial
> number.
>

IIRC, the plastic used was of a type that was hard to synthesize at
lower TL's, and had diffraction gratings and such that made it harder
to duplicate at higher TLs.

T4 added the "Credit Verifier" which would check credits to make sure
they were real.
I'd suspect some kind of non-invasive chemical check of the bill -
"sniffing" it for chemical traces, or maybe some kind of spectography.