[Tagging] Zones and defaults [fork from: access in the wiki]

althio forum althio.forum at gmail.com
Fri Dec 5 15:13:12 UTC 2014

> "defaults" are something for that data consumers need when actual data is
> missing. ;-)

YMMV... My current point of view is different:
+ "defaults" are something to make tagging easier and more efficient.
+ They allow redundant data to be missing and thus make the database
cleaner and smaller.
+ If the default value must be changed (e.g. the regulations are
changing) the bulk of the modifications is smaller.

Also please imagine a new local mapper willing to add data. If it is
easy to improve a bit the map with one straightforward tag (e.g.
highway=living_street) then documentation, translations, answers and
mapping are easier for everyone.
If it needs a full chain of tags:
highway=residential + motorcar=private + emergency=yes + psv=yes +
disabled=yes + ...
and full understanding of the access key, access wikipage, in English
only; acronyms, caveats like access=yes and access=no...
That is another story altogether. One single error in the tagging can
screw it all.
Maps are done also by local people for local people. Not only by very
experienced OSMers, skilled with computers and fluent in English for
fellow taggers.

> IMHO this should not be used to remove tags that are
> defined as "default".

Not proposed, not mentioned, not in my mind.

> In a system like OSM you always have the problem that
> the absence of a tag can mean 2 things: incomplete data/mapping or default
> data. Until you add the tag you won't know.

That is right.
And this is something I can live with.

If I wanted to address this issue as simply as possible:
e.g. highway=* + [maxspeed not set] is mapped correctly and the
default maxspeed is adequate.
But I want to indicate that maxspeed is known for real and it is not
incomplete data:
-> highway=* + maxspeed=default

Of course some people are not favorable to defaults or they have
different limits on what is acceptable.
So any discussion on the subject is a hard one.
If there is no consensus on "using defaults: yes or no",
it becomes difficult to discuss how to choose default values,
how to tag values identical to default, and so on...

> Please search the archive, this was discussed several times in depth.

Nice proposition. Searching="default" is always a good start but...
would anyone care to point other keywords that could lead to
interesting discussions?
Also is there some meaningful wikipage and proposals
[draft/rejected/accepted...] specifically on the subject of defaults?
other than:

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