diff --git a/RELNOTES b/RELNOTES
--- a/RELNOTES
+++ b/RELNOTES
@@ -10,6 +10,16 @@
 
 Changes to this file should not be MFCed.
 
+f0600c41e754-de701f9bdbe0, bc201841d139:
+	mac_do(4) is now considered production-ready and its functionality has
+	been considerably extended at the price of breaking credentials
+	transition rules' backwards compatibility.  All that could be specified
+	with old rules can also be with new rules.  Migrating old rules is just
+	a matter of adding "uid=" in front of the target part, substituting
+	commas (",") with semi-colons (";") and colons (":") with greater-than
+	signs (">").  Please consult the mac_do(4) manual page for the new rules
+	grammar.
+
 02d4eeabfd73:
 	hw.snd.maxautovchans has been retired. The commit introduced a
 	hw.snd.vchans_enable sysctl, which along with