[Tagging] trees and waterways

[Tobias Knerr]

Nathan Edgars II wrote:
> On Sun, Sep 12, 2010 at 4:37 PM, Pierre-Alain Dorange <pdorange at mac.com> wrote:
>> Yes i understand, but own could you figure "flow=downstream" exist ?
>> You must read a "manual" to know that.
> 
> By noting its presence on an already-mapped waterway. And if you don't
> know about it, at least you aren't doing anything wrong by leaving it
> off.

Nevertheless, I don't think we need to require a tag like this. Why?
Because there's an even more effective way to make a mapper aware of
problems with the data: Maps that look wrong!*

The problem with flow direction right now is that it isn't actually used
by any popular application, so a mapper can continue to edit and not
notice the issue for a long time. However, the lack of applications
using it also means that errors aren't all that bad. As soon as
applications using the tag become more widespread, people will notice
the (then visible) errors and start to correct them.

Tobias Knerr

* Or any other application that behaves wrong, of course.