This changeset deleted part of the boundary of Sterling, VA (osm.org/relation/2669756).

Hello, you have broken the boundary:
osm.org/relation/8527041

What a bizarre little town! Anyways, in this edit you left a bit of street hanging off the boundary which broke validation. I've fixed it but you should probably check that it's correct.

Hello, this change broke the Carrboro boundary relation (osm.org/relation/179859). Please be sure to use the JOSM validator to prevent this from happening!

Hello, please be aware that this change broke the Jeffersonville boundary relation (osm.org/relation/127622). I've fixed it, but in the future please be sure to use the JOSM validator to prevent this issue!

Hello - this change broke the Westerly town boundary relation (osm.org/relation/7723824)

Hi, please be aware that this change broke the Asheville boundary polygon. I've seen this happen several times on your North Carolina city edits.

I see now that one of the sets of polygons includes the over-water parts. Thanks for pointing this out. I'll work on putting that back.

Hi,
I've been using the GIS data (dated Sep 2019) at: https://docs.digital.mass.gov/dataset/massgis-data-community-boundaries-towns-survey-points

It states "This layer is the most accurate representation of Massachusetts' municipal (city and town) boundaries; this representation is based on the legislatively approved record of municipal boundaries."

Is there a different data source I should be using instead?

The exclave is fine, but the change broke several local and international boundary polygons. For example, the exclave should have been "inner" for Costa Rica, and the polygon for the town "Colorado" was left unclosed. I've fixed the worst of these issues in the changeset below, but there are still quite a few things reported as broken in JOSM in that area.

osm.org/changeset/86463655

Hello, this change broke the border of Costa Rica.

Hola, este cambio rompió la frontera de Costa Rica.

Sure, what towns do you have in mind?

I agree with you on the neighborhood markers. However, the community boards have defined boundaries listed on NYC.gov, so there's really no question about where they start and end. From an OSM perspective it doesn't matter how much political power they have, the question is whether they represent administrative divisions. At one point someone removed the Rhode Island counties and they ended up being restored even though they existed in no real way other than having defined boundaries. I don't have any skin in the game either way but I can see why there likely wouldn't be consensus to get rid of them.

I ran into a similar thing in Hawaii trying to map the cities and towns. Turns out there aren't municipal boundaries so that was an exercise in frustration. However, in defense of the Manhattan community boards, they do appear to be real administrative entities subordinate to the boroughs.

There is a discussion at: osm.wiki/Talk:United_States_admin_level

Might be worth raising the question. The same discussion was had about Rhode Island counties which are not administrative either but ultimately were kept at admin level 6.

This change broke the bounding polygons for Manhattan Community Board districts, relations:
7340078
7340074
These relations are currently unclosed polygons.

Thank you for helping to get this corrected in spec, Alexey.

I encountered this issue when developing an application that was attempting to load a list of countries. Imagine my surprise when only Indonesia, Djibouti, Cyprus, Monaco and Vatican City showed up in the data set!

I have added a proper center point for Indonesia, and added to the Indonesia relation, so this should satisfy the objection.

I removed a tag from a relation that was not valid according to the spec. Any processing that depended on that tag was invalid. Only a few countries were incorrectly tagged in this way.

Please feel free to add a place=country node.

Thanks for catching this. You're right, place is intended to be a node key. I undid this.

I ran into 5 other countries coded this way: Monaco, Vatican City, Indonesia, Cyprus, and Djibouti so I went ahead and removed the place tags from those relations as well.