[Tagging] any tag you like, but why create parallel systems for established tags? DCGIS

Martin Koppenhoefer dieterdreist at gmail.com
Sat Mar 10 11:38:18 GMT 2012


I recently stumbled upon an import in the US prefixed with "dcgis".
While this tagging makes it possible to have these data inserted
parallely to other OSM data I still wonder why someone would do that.

In particular I am refering to this:
http://taginfo.openstreetmap.org/keys/dcgis%3Aaddress

I don't see the point why this is not the usual "addr:street" etc.


and there seem to be also other issues:
http://taginfo.openstreetmap.org/search?q=dcgis

The most used tag in this "namespace" is "dcgis:captureyear"
http://taginfo.openstreetmap.org/keys/dcgis%3Acaptureyear
which can be found 93 022 times in the db but isn't documented in the wiki [1]


Looking at the key name and values this looks like the date when the
external database included the object in their system. Why on earth
should we keep track of this in OSM? Doesn't seem to be a
geoinformation to me.

How should a mapper deal with these tags if he modifies an object?
E.g. if there is a dcgis:acquired=6 (
http://taginfo.openstreetmap.org/keys/dcgis%3Aacquired ) on an object
he splits?

I suggest to modify [1] to not further encourage people to import all
of the information from dcgis into osm, but only those that are
useful.
E.g. these sentences could be modified:
"SSL and AID - The AID and SSL attributes are used to correlate the
data with the DC MAR (Master Address Record) and should generally be
preserved."
"Pubdate - DC-GIS data includes a pubdate in the supplementary XML
file. This should be included in the features as dcgis:pubdate and the
date should be reformatted to YYYY-MM-DD"
"Dataset - In order to preserve the origin of the data, the dataset
should be specified. The naming of these datasets should map to the
naming of the zipfile, ie PostOfficePt or ParkPly, the resulting key,
value pair would be dc-gis:dataset=ParkPly"

These are the keys named in the wiki, but the actual data contains
much more keys, which aren't obvious in their meaning (at least to
me), or which are almost pointless in a spatial database, or which
would be much better suited for a changeset comment then for a tag on
the object, e.g.
dcgis:area
dcgis:gis
dcgis:length
dcgis:list_info
dcgis:nr_eligibl
dcgis:update_date
dcgis:url

cheers,
Martin


[1] http://wiki.openstreetmap.org/wiki/Washington_DC/DCGIS_imports



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