"Dong" is on VN paper money as well. "Piaster" or "P" is a term left over from the 50s and used interchangeable with the Dong. Same as we use dollar/buck/etc.Dong was the SVN coins and Piaster was their paper money.
I sent home a variety of both.
Really the Dong was closer to penny/cent than a buck when I was there....and it got much cheaper down the road.