form_hook(3) on FreeBSD
The text b927f7f7e09e, as FreeBSD 12.4-RELEASE, FreeBSD 12.3-RELEASE, FreeBSD 12.2-RELEASE, FreeBSD 12.1-RELEASE, FreeBSD 12.0-RELEASE, FreeBSD 11.4-RELEASE, FreeBSD 11.3-RELEASE, FreeBSD 11.2-RELEASE, FreeBSD 11.1-RELEASE, FreeBSD 11.0-RELEASE shipped it.
set hooks for automatic invocation by applications