[OSM-talk] Map Features tagging question

[Etienne]

Nicola
I've been promoting the idea of namespaces for some time.  When I create
tags which are for my own personal use, and not have any specific meaning to
anyone else then I prefix them with my user Id.

So any tags, or values starting 80n: are mine and will not have (much)
meaning to anyone else.

One example.  When I tag a way with a street name, I add the filename of
photo that I used as a source as image=80n:dsc01234.jpg.  Many people may
have a photo with a filename of dsc01234.jpg, but the 80n prefix identifies
it as referring to _my_ photo.

Another example.  I wanted to render a map that showed all major roads in an
area but only a selected few unclassified roads.  I tagged those roads I
wanted with 80n:ibm=yes and then used a modified version of the osmarender
rules file to only select ways that had that tag, like this:

<rule e="way" k="80n:ibm" v="yes">
  <rule e="way" k="highway" v="unclassified">...</rule>
</rule>

The purpose here was to show only the relevant roads leading to a particular
IBM facility, and suppress all the irrelevant roads in the area.  It worked
quite well.

Etienne


On 7/20/06, Nicola Ranaldo <ranaldo at unina.it> wrote:
>
> On Thursday 20 July 2006 10:28, Andy Robinson wrote:
> > No, you are absolutely right, nearly everyone wishes to see a level of
> > consistency. The trouble is not everyone wants to use the OSM data for
> the
>
> [...]
>
> > tags that are already there. Existing tags should never be deleted if
> > possible in case they are being used by someone.
>
> From a developer point of view:
>
> * when a user enter a tag for an osm object, this information is available
> for
> everyone in the world
> * this information should be useful for the community and not for private
> needs (use your hard disk for that :))
> * this information in the 99% of cases will be used by the software and
> not by
> humans!
> * the software does not know the human meaning of a tag but has to follow
> a
> well-defined set of rules
>
> ==>
>
> * you should enter data in osm if well defined!
> * you should fix data in osm if not well defined!
> * before adding an undocumented tag in the system post an rfc on the
> mailing-list
>
> If this is against the freedom (to construct an unusable data set?), we
> should
> separate tags in "namespaces", and reserve an XXX official namespace only
> for
> common rendering/viewing/routeplanning where data integrity is strongly
> enforced. Other namespaces could be free (to construct private data set?)
> if
> we really need them. Editors and viewers could be free or XXX compliant.
>
> The same concept should be applied to data primitives, we should strongly
> define them and enforce data integrity on the database, for example the id
> is
> an integer > 0 and in the osmplanet there are ways with segs with a
> negative
> id. Are two segments from x to y and from y to x admitted? Are two nodes
> with
> the same lat,lon admitted? Actual editors take care of those?
> As specified in the "Data Primitives" wiki page, ways and areas are
> objects
> with the same elements. Is necessary to separate them? If not what are the
> differences? these are simple examples, but while coding osm "clients"
> they
> affects data structures more then a bit, and shows strange paths when
> doing
> route-planning!
>
>         Niko
>
>
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