--- base/doc/port.1.orig	2010-06-18 16:08:45.000000000 -0700
+++ base/doc/port.1	2010-06-18 16:09:29.000000000 -0700
@@ -129,7 +129,7 @@
 .Pp
 .It
 .Ar leaves :
-installed ports that are unrequested and have no dependents.
+installed ports that are unrequested and have no dependents. Note that leaves could be build-dependencies of requested ports and may be required for upgrades of those ports.
 .Pp
 .El
 Sets of ports can also be specified with