From OpenStreetMap Wiki
|[[Image:|240px|One example for collection]]|
|(via overpass turbo - help)|
|Relations are not Categories. You should not create relations to group all objects of a certain type in an area. For example a relation listing the coastlines of Wales does not belong in OSM. If you wanted to find all the coastlines in Wales you could do so with the Xapi, Overpass API or Osmosis.|
Description page for the proposed relation collection.