[Talk-us] Network tag Re: Highway Shield Rendering

[Phil! Gold]

* Paul Johnson <baloo at ursamundi.org> [2012-04-04 14:01 -0700]:
> OK, I'll bite.  How is putting banners in the network tag
> preferential?  why not something like...
> 
> network=US:TX:FM
> modifier=Business
> 
> network=US:US
> modifier=Business
> is_in=Maryland

Each of the potential tagging schemes had drawbacks.  One of the chief
drawbacks of this one is that a naive data consumer that looks at the
network and ref tags but not the modifier tag will get drastically
incorrect results.  (If it looks only at the network tag, then that's
useful information on its own.  If it looks only at the ref tag, it's not
that useful, but it's also not likely to come to incorrect conclusions
about the data.)

For the record, the drawbacks of the other approaches are:

 * network=US:US, ref=50 Business
   Mingles base reference numbers and route modifiers together in a way
   that's difficult or at least annoying for data consumers to process.
   Addressing this problem was one reason for separating the network and
   ref tags on route relations in the first place.

 * network=US:US:Business, ref=50
   Separates mainline routes from their alternates and variants, even
   though all of them are, outside of OSM, in the same road network.
   Complicates things for data consumers who care about the main network
   but not whether a route is a mainline or variant (not that there are
   any such consumers that I know of, but it would be a problem for
   them).

-- 
...computer contrarian of the first order... / http://aperiodic.net/phil/
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