Which software/tool is using this information?
It should not harm to add this tag to the capital cities, but I’m not sure of what will be the application?
Is nominatim using it? I guess not.
That world-wide use of this tag is quite limited.
So if it makes you happy, go on.
The more widely used approach to tag this information is to add a member with the role admin_centre to the boundary relation.
is_capital is used 600 times world-wide whereas admin_centre is used 86.000 times.
I am not sure, but something like that could work:
place=* & mkgmap:admin_level4=* [your code]
I’d like to try that out somewhen…
Tried that this morning - and had to find out that it does not work. I posted a question to the mkgmap mailing list: http://gis.19327.n5.nabble.com/Provincial-capitals-td5779330.html
Perhaps the experts will know a better solution.
Using admin_level=* would allow for the possibility of applying this to other administrative levels as well. The is_capital=* tag would also run into problems as soon as you tried to expand to cover multiple countries. (State vs province, county vs district, etc.)
The capital_level=* tag currently used in several places in Thailand doesn’t seem to be used anywhere else.
great you managed it without is_capital.
Is the general thing: more prominent rendering of capital towns a thing we would be looking for on the main map as well? Maybe even on osm.org?
Next weekend I plan to improve the rendering, at least prepare the rendering stack for the improvements. As you sound quite tech-savy, could you help in suggesting improvements and in determining how to implement it?
More on a dedicated thread: http://forum.openstreetmap.org/viewtopic.php?id=22714