Hi. I was expecting to hear from someone about this. Yes, it's a local mapping project. We'll be using this for authority control. I've just added a row to the "Extensions" section of the Key:ref article on the OSM Wiki, with the following text:

> A unique identifier for features on Bainbridge Island, Washington, United States, that while of local importance are not significant enough be included in Wikidata.

This might be more at home in the "Special uses" section, or even "Authority control". I've not been on any of the OSM forums or Slack channels recently, but if you can recommend a venue for me to discuss this, I'd love to get others' thoughts.

Just as Wikidata does, we'll be linking the other way also, to OSM entity IDs, but this a fallback. It's a fallback that might well be utterly unnecessary. I guess really I'm concerned about features being removed or replaced and us losing the connection, but we'll have enough bots watching for this as part of our QA, and it's only a small island, I think we'll be okay.