My First Rolex! Any help on history would be appreciated!

[euphoniumplayer1]

Hi all, Just acquired my first Rolex a really nice Oyster Brevet from I think 1966. I can't really make out the serial except for the first two numbers which are a 1 and 8 I think through research puts it at 1966. It also has Brevet with a + next to it on the 12 position. The crown doesn't have a Plus or Brevet on it but a dash at the bottom. Not really sure what Brevet is though. It is in great condition and keep really awesome time for being a 47 year old movement! Any info on this piece would be appreciated! Thanks!!