char.bom
Almost always an editor on Windows that saved the file as “UTF-8 with BOM”, or a script that wrote it with Python’s utf-8-sig. Nothing renders differently, which is why it survives review.
What it means
Section titled “What it means”A byte-order mark at the start of the file: not text, and a byte the round-trip compares, so the file stops matching what the schema renders.
The mechanical pass reaches it: roadkeep lint --fix closes this one.
What closes it
Section titled “What closes it”roadkeep lint --fix— the mark is deleted, and no other byte moves