[Tagging] Waterway direction

[Nathan Edgars II]

On Tue, Aug 31, 2010 at 4:10 AM, M∡rtin Koppenhoefer
<dieterdreist at gmail.com> wrote:
> a) you will add a note or FIXME to express this to the following
> mapper. At least you have a 50% chance that it is already right.

Perhaps you can explain how I or anyone else will determine the
direction of this waterway: http://www.openstreetmap.org/?way=73765043
Should I ask one of the residents if I can go into their backyard and
dump food coloring in the water?

I don't know of any other feature where the direction of the way means
something *without* another tag being added. I've traced a number of
waterways from aerials and never had any idea I was supposed to set
the direction of the way equal to the direction of flow.