[Tagging] leisure=common

[Christoph Hormann]

On Monday 04 May 2020, severin.menard via Tagging wrote:
>
> With this approach we would need to create a lot of new tags, eg for
> highways. Primary, secondary and tertiary are hierarchy based and
> does not mean the same reality everywhere, This is why
> https://wiki.openstreetmap.org/wiki/Highway_Tag_Africa has been
> created. When you travel, roads, hospitals, schools, bakeries do not
> look the same but broadly intend to provide similar services.
> "publicly-accessible land worldwide" is the definition in the wiki
> for leisure=common and IMO it fits well for defining those kinds of
> pieces of lands you cannot miss on imagery and whose status/functions
> are not as precise as for parks, recreation grounds, etc.

Note there are real world features which are semantically very similar 
despite looking very different - imagine a soccer field in central 
Europe with green grass, one in subtropical Africa with bare ground, 
one in Greenland with artificial turf and one on a glacier in the 
Antarctic with compacted snow, all tagged leisure=pitch.  But there are 
also features which at a quick look have semantic similarities (public 
spaces in this case) but where this smallest common denominator is too 
broad for it to have much practical meaning and there are tons of 
features all over the world that fit that definition but for which 
there are many different existing and more precise tags.

We from our European/North American often without thinking try to apply 
our cultural perspective and classification to environments physically 
and culturally very different from our own.  We currently have almost 
zero tags with somewhat broader use in the OSM database that were 
invented outside of Europe and North America (counting Russia as Europe 
here - the Russian community is relatively active in establishing new 
tags).  That is not normal and indicates a serious inbalance.

I think - like often in tagging discussion - that too much focus is put 
on what tag to use and too little focus on what you actually want to 
map.  And i don't mean what object physically to map on the ground but 
what semantic aspect of it you want to map.  The problem here - and 
that already became clear with the initial post by Jean-Marc - is that 
there are a multitude of aspects that define these locations.  It would 
be appropriate to tag these aspects as such and not try to identify a 
specific combination of characteristics from a type locality and then 
try to apply this to other locations.  That is not very useful, in 
particular for cultural geography features - no matter if it is a new 
tag or it it locally re-purposes an existing tag.

So my suggestion how to proceed here:

* take a good look at the area you want to map things in.
* identify what specifically you want to map.
* formulate in an abstract form (i.e. not definition via examples) and 
avoiding weasel words like 'generally' 'typically' or 'usually' the 
common and verifiable aspects of what you want to map.  Such aspects 
can be physical (in case of areas of land:  state of the ground, what 
kind of objects are located on it etc.) or cultural (like what function 
the feature has for the locals, how it is used by humans etc.)
* look for existing tags that already indicate things you have 
formulated.  Invent new tags when needed.  Clarify documentation of 
existing tags when needed.

The third step - formulating your classification in abstract form 
*before* you assess if existing tags are suitable - is key here.

-- 
Christoph Hormann
http://www.imagico.de/