Note from US immigration in passport?

Question

When I travelled after Sept. 11th 2001 from Switzerland to the US I had an annoying passenger next to me with his cell phone on all the time -even during the flight and so I reported him at US immigration.

After they "caught" this guy the US Immigration Officer wrote "MFP (or MRP) Advised" next to the immigration stamp in my passport.

Does anyone know what this means or could mean?

Answer 1

MRP is "Machine Readable Passport"

It has nothing to do with your incident.  It's to notify anyone else checking it that you had already been reviewed at the immigration counter.