Index: head/sys/kern/capabilities.conf
===================================================================
--- head/sys/kern/capabilities.conf
+++ head/sys/kern/capabilities.conf
@@ -28,6 +28,11 @@
 ##
 ## List of system calls enabled in capability mode, one name per line.
 ##
+## System calls listed here operate either fully or partially in the absence
+## of global namespaces or ambient authority.  In capability mode system calls
+## that operate only on global namespaces or require ambient authority have no
+## utility and thus are not permitted.
+##
 ## Notes:
 ## - sys_exit(2), abort2(2) and close(2) are very important.
 ## - Sorted alphabetically, please keep it that way.