BFO 2020

ISO/IEC 21838-1 Top-Level Ontologies (TLO) (= Part 1 of a multipart standard; specifies the requirements for being a TLO)

published by ISO in August 2021 at https://www.iso.org/standard/71954.html

freely available to those working on standards at this ISO site

ISO/IEC 21838-2 (= Part 2, which standardizes BFO as a top-level ontology conforming to Part 1)

https://www.iso.org/standard/74572.html

This too will be freely available from ISO at the same link.

The entire formal content of BFO-2020 is available here:

https://standards.iso.org/iso-iec/21838/-2/ed-1/en/