I don't see a problem with duplicating a tag in both the relation and
sections of the object.  In my case I have been mapping the national
highway network of Turkmenistan the last few months.  I have created
relations so that all segments belong to one or more highways (P-1 from
Ashgabat to Koneurgench, for example).  However, most map renderers will
not indicate that, plus the road is known to locals in most areas by
that name, so I have also added it to the name=* and ref=* tags.  Too
much data?  I don't think so.  Each tag serves a slightly different
purpose, and the relation serves a wholly different purpose and is not
visible in most map products.

Please don't go to the Turkmenistan map and delete all my hand-entered
tags on the highways!

Allan Mustard


On 11/2/2018 5:04 AM, Dave Swarthout wrote:
> Putting aside the discussion about type for a moment, this topic
> relates to a discussion I'm having with a user about tags and
> multipolygons, specifically where the tags go, so I believe it fits
> into this discussion. I removed the tags from the ways for a section
> of the Trans Alaska Pipeline (TAP) because those same tags were on the
> relation itself. The user asked in a changeset comment why I had done
> that. I replied that IMO, any tags that applied to the pipeline as a
> whole belong on the relation and need not, indeed should not, be
> repeated on each way. The TAP is 1300 km long, has countless bridges
> and sections where it is underground and then overground. The only
> tags that should appear on the ways themselves are attributes of those
> ways, for example, location=overground or location=underground, and
> tags for bridge and layer. Everything else, Wikidata, substance=oil,
> man_made=pipeline, etc, should appear only on the relation. The folks
> who added the pipeline mostly via Tiger imports many years ago tagged
> both. When I would occasionally add or replace a section, I was always
> careful to copy all the tags from a neighboring section to the new
> section. Now, I think that is incorrect.
>
> If those tags appear on each way in addition to the relation,
> maintaining any consistency in the tagging on this beast would be
> almost impossible. I have done quite a bit of re-aligning of the TAP
> over the years as our available imagery improves but have always been
> tentative about removing those redundant tags thinking I would get
> around to it someday. In fact, it seems apparent that this is one
> major reason relations were invented, especially for objects like
> routes — to ensure tagging consistency and connectedness between the
> many individual member ways that comprise the whole.
>
> So, what is the correct and accepted way to tag something like the TAP?
>
> Dave
>
> On Sat, Oct 13, 2018 at 7:17 AM Kevin Kenny <kevin.b.ke...@gmail.com
> <mailto:kevin.b.ke...@gmail.com>> wrote:
>
>         why not a multipolygon? I agree that you don’t need additional
>         tags for a group relation, just type=group, a name and the
>         members, but for a site you would need something that
>         describes the site, a tag for a group of water areas, so as
>         long as all the members are areas (or parts), a multipolygon
>         would be better.
>
>
>     When the lakes themselves are complex multipolygons with many
>     islands, repeating that data for the group is likely to be a
>     maintenance nightmare. (I know this from curating
>     boundary=protected_area relations that include partial shorelines
>     on such lakes. It's especially fun when the boundary splits islands.)
>
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>
>
> -- 
> Dave Swarthout
> Homer, Alaska
> Chiang Mai, Thailand
> Travel Blog at http://dswarthout.blogspot.com
>
>
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