sticky(8) on OpenBSD
The text 5627a255beb1, as OpenBSD 7.3, OpenBSD 7.2, OpenBSD 7.1, OpenBSD 7.0, OpenBSD 6.9, OpenBSD 6.8, OpenBSD 6.7, OpenBSD 6.6, OpenBSD 6.5, OpenBSD 6.4, OpenBSD 6.3, OpenBSD 6.2, OpenBSD 6.1, OpenBSD 6.0, OpenBSD 5.9, OpenBSD 5.8, OpenBSD 5.7, OpenBSD 5.6, OpenBSD 5.5 shipped it.
sticky text and append-only directories