Road reference number format

I found several reference tags in Turkish roads contradicting each other. Unfortunately the road signs are also not consistent. For example I have seen “D-100”, “D_100”, “D 100” and “D100” used for the same road.
At least for motorways (otoban) I have seen consistent use of “O-1” etc.
I couldn’t find a tagging guideline on the page.

What’s the recommended tagging practice for road reference numbers in Turkey?

That differs even on street signs :wink: Have a look at D.300 photos 1 and 5 atürkiye/Timeline for example…
The Turkish wikipedia uses a dot as in

Has there even been achieved some consensus within the active Turkish OSM mapping community, which format would be preferred in OSM?

Hi Claudius, we’ve met at Heidelberg.

Unfortunately there is not a consensus within the community, but when I checked the international convention, the naming seems to be E5, D100 etc.

It is also common to use dash and state as E-5 or D-100 as well. My logic tells me the former, without dash.

And then there is the actual road signs which say “D.100” which aligns with the English Wikipedia articles and highway crests:
But the Turkish articles have a space while still using the “English” highway crest images with the dot. And finally German wikipedia writes them directly together:

Turkish General Directorate of Highway maps are here:
They use dashes for motorways “O-30” and some non-breaking space (or no space, hard to tell from the inconsistent map layout) for state roads “D 550”. Waaaah!

Following the “map what’s on the ground” (==road signs) rule of OSM we should actually use the “D.100” and “O.3”, but it feels like the dash notation for motorways and no space (since non breaking spaces are very hard to tell apart from normal space) for state roads.
I would suggest to document something on the OSM wiki Turkey project page.