From OpenStreetMap Wiki
|coastline:survey_quality = inadequate|
|Denotes a coastline traced from an unreliable source, in the form of interpolation, or where partial survey concludes that the coastline is plainly wrong|
|Used on these elements|
|Tools for this tag|
This tag is meant to show a coastline where survey data is of a bad quality, low, plain wrong, or from an extremely unreliable source.
This tag allows renderers to differ between survey quality in accordance with INT 1 symbols C1 and C2.