Hey, Runatic!
Road-course measurement uses a factor of 1.001 to guard against a course accidentally being short.
That amounts to an extra meter for each kilometer measured. It's built into the measurer's calculation, not permission to cut the course or a target for your GPS watch.
Even a kilometer gets a small margin for error. Read more
One month to Abu Dhabi: December 12. The program also includes a two-person marathon relay. Event schedule