http://tools.geofabrik.de/osmi/?view=coastline&lon=123.00069&lat=-4.96481&zoom=12&overlays=coastline,unconnected
Between these two
http://www.openstreetmap.org/browse/way/164757973
http://www.openstreetmap.org/browse/way/150057335
I checked, it was not a missing tag, the way where the coastline used to be is no longer there.
I could not find the changeset and there must be a better way to restore that redrawing using background images.
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according to http://zverik.osm.rambler.ru/whodidit/?zoom=13&lat=-4.8888&lon=123.02125&layers=BTT&age=1000 i’d guess it was http://www.openstreetmap.org/browse/changeset/13567838
yes, it was it. Actually the same user has deleted it twice according to the history of this way. I was able to restore it quite easily, though.
http://www.openstreetmap.org/browse/way/25865914
The history in potlatch2 tells us that user ‘Peter14’ has edited the same way on 2012-10-10 with comment “restored deleted coastline”. Both mine and Peter14 editing was done after same user.
I have sent the user a message telling that unless he comes up with a decent explanation to this thread, I have to report this as vandalism. You can make a mistake, but making same mistake twice is not learning.
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Now the same user has deleted it again.
It seems the user is redrawing the coastline probably from the bing imagery, but deleting a long part and redrawing it only partially (and not adjusting the rivers) is not a proper way of doing it.
I split it into two and joined again in both ends. It got a new number.
http://www.openstreetmap.org/browse/way/187748244