[Tagging] Short-term parking zones

[pbnoxious]

Hello,

I never thought about this before and it would open up a totally new way 
of tagging things. But I have some questions/comments:

1) How does this exactly work and do the usual applications expect this? 
E.g. would it work to add a tag to an otherwise untagged way that refers 
to a relation with the tag "highway=residental" and the way would be 
rendered correctly?
As I can't remember any such usecase and couldn't find one: Is there an 
example where this is already used?

2) I feel like this is not really the intended use of a "relation" as 
this does not really "relate" objects but rather works as a sort of 
"category" or a way to define individual collections of tags. I can see 
the advantage of having such a shortcut, but for me it doesn't 
intuitively fit together with the current definition/use of relations.

3) If this were used more widely, i.e. users would use relations to 
group tags that can be applied to many similar objects this might lead 
to some more problems:
Possibly individual users would create their own relations with their 
often used tag combinations, which probably results in a lot of 
identical relations (empty relations with the same tags). Actually I 
wouldn't know how to search for an empty relation with a set of tags, 
but maybe any of you do.
Also one would have to strongly document these relations e.g. in the 
wiki to prevent the creation of duplicates and make them accessible for 
new mappers. This would result in them being sort of proposed "tag 
collections" or "tagging helpers". Interestingly similar approaches 
already exist for some special cases (e.g. "crossing=zebra" is a 
shortcut for the tags "crossing=uncontrolled" and "crossing_ref=zebra"), 
but of course the difference is that tags are here not explicitely 
included. While this might faciliate things for experienced taggers 
(that know the corresponding relation numbers or where to look them up) 
it is very unintuitively and hard for new mappers. A more intuitive way 
would be some sort of "user created tags" that do exactly the same 
thing: collect tags and values into a new one that can be referenced by 
it's name (rather than some arbitrary number). Of course this would 
require major changes in the whole way OSM tagging works (which I do not 
want to propose here)
So although relations can (probably?) do this, I don't feel like using 
them this way would be good.

Generally I think this is a topic that needs a lot more discussion 
before I'd encourage anyone to use such empty relations, especially as I 
couldn't find any documentation except for the one wiki site you provided.


Kind regards
pbnoxious