A quay is a length of coast designed to allow vessels of some size to moor alongside the shore. In an industrial harbour a quay may have cranes and facilites to unload cargo. For passenger vessels it may have facilities for passengers to embark. A quay will normally be tagged as part of the coastline natural=coastline.
In a scheme analogous to man_made=pier, a quay may be modeled by tagging a section of the natural=coastline as man_made=quay.
For named quays, use name=*