[OSM-newbies] Tagging with PFM

[Serge Wroclawski]

On Sat, Sep 25, 2010 at 8:55 AM, Gavin Scott <gavincscott at gmail.com> wrote:
> More Info.
>
> On a road drawn by someone, is tagged as
>
> highway secondary
> PFM:RoadID  127
> PFM:garmin_type 0x3
>
> I believe this forces the road to display in a certain way in teh gps. But I
> was also wondering if this is the 'proper' way to tag.

I don't know what PFM is, and I think that was the question being
asked by Dave. Googling didn't reveal anything.

If it's what Leonard thinks, some Garmin internal thing, then I'll
second what he said, with some elaboration.

OSM is a database of geographic information. The end product of this
database is a variety of representations and formats. We have the
Mapnik rendered slippy maps, the OSMRender maps, the Halcyon renderer,
tactile printed maps, garmin format maps, and more.

The rule is, we tag the data, and then there's a program somwhere
which handles the display process. We usually call that a renderer.

In the case of the images in the slippy map, the renderer has a bunch
of rules that say things like "If the way is tagged as a highway, then
draw the line with a large width and in the color blue" and "If
there's a way tagged as a building, draw the way with a thin black
line, filled in with brown".

So if secondary roads in OSM map to Garmin type 0x3, the program which
converts one format to the other will take care of that. That leaves
the data separate from the presentation, which is a really core part
of OSM.

- Serge