[OSM-newbies] Direction of streams / rivers

[Bogus Zaba]

Sorry if this is a stupid question. I am new to the list and to OSM 
mapping.

What is the convention for direction of streams and rivers? I assumed 
that the direction of the way would be the same as direction of flow in 
the stream. However in many cases in my locality I see that it is 
opposite, ie the direction of the way is upstream - from sea to source. 
Is there a correct way to set this direction?

Thanks

Bogus