Found the Parking lanes viewer from OpenStreetMap project, which tries to visualize the parking lanes.

For Graz, this looks like this: https://zlant.github.io/parking-lanes/#15/47.0704/15.4303

Unfortunately, the viewer takes parking:condition:left:time_interval into account and does not show the parking lanes if you have a time set which is out of the time_interval, see: https://github.com/zlant/parking-lanes/issues/19

Created a feature-request to make the time-dependent view optional (https://github.com/zlant/parking-lanes/issues/43)

Quoting Tennis court / Surfaces from Wikipedia:

Tennis is played on a variety of surfaces and each surface has its own characteristics which affect the playing style of the game. There are four main types of courts depending on the materials used for the court surface: clay courts, hard courts, grass courts and carpet courts.

As this is the main information a tennis player is looking for when looking up a tennis court, I think using these four values for the “surface” key should be fine.

And yes, the ITF classifies 9 types and I would also like to classify these “surface codes” too, but I think it is not so easy for an average person to identify the correct surface type. What about using a subkey “surface:code” or “surface:type” to tag this information?

The most famous tennis courts would then be:

Australian Open / OSM: Surface is “hardcourt”. Surface manufacturer is “GreenSet”. Surface Type (according to ITF) is “Acrylic/Polyurethane”. Tag proposal: “surface=hardcourt” and “surface:code=A” and/or “surface:type=Acrylic”.

Wimbledon / OSM: Surface is “grass”. Surface type is “Grass”. Tag proposal: “surface=grass” and “surface:code=H” and/or “surface:type=Grass”.

French Open / OSM: Surface is “clay”. Surface type is “Clay”. Tag proposal: “surface=clay” and “surface:code=F” and/or “surface:type=Clay”.

US Open / OSM: Surface is “hardcourt”. Surface manufacture is Laykold. Surface Type is “Acrylic/Polyurethane”. Tag proposal: “surface=hardcourt” and “surface:code=A” or “surface:type=Acrylic”.

I am aware that :lanes are valid tags. Although I am absolutely not “into” railway/tram mapping/tagging, the problem (I have) here is that in this case (1,2) that the tram way is (has been) mapped separately (in the meanwhile?) (aka the “trams run two lanes on a road that is not structurally separate in directional lanes” and the “tram tracks are drawn as two ways and the road as a way in between”, quoted from tram).

So the question for me now is, if the tram has been mapped separately, should there still be a https://wiki.openstreetmap.org/wiki/Tag:railway:lanes=tram key on the main road?

Hi highflyer74!

Thank you very much for reaching out!

First, please give me a chance to give a short response with my thoughts about your comment:

• My blog/diary is just what it is: a journal / diary about things I do, learn and encounter around OSM. I feel a bit flattered that someone (you) even read my article and I am grateful for your comments. But I really had no intention on starting a discussion here (at most this blog (entry) is a reminder to myself in case I have a chance to talk to experienced OSM mappers).
• Actually, what are the prerequisites for a valid tag? I “know”, a Wiki article is not mandatory, but I never was able find a definite answer. (The closest I could find is here and I think mapping should be consistent (at least as much as possible).)
• You are right, but still: ~300 - ~500 tags in 5 cites (in Europe) do not seem very “well-established”.
• Talking to the local community is a must, sure.

Long story short: I will reach out to the local OSM community and ask for their opinion. Thanks again for you comment.