Index: head/tools/build/options/WITH_META_MODE
===================================================================
--- head/tools/build/options/WITH_META_MODE	(revision 297843)
+++ head/tools/build/options/WITH_META_MODE	(revision 297844)
@@ -1,3 +1,12 @@
 .\" $FreeBSD$
 Create meta files when not doing DIRDEPS_BUILD.
-The meta files can be useful for debugging.
+When the
+.Xr filemon 4
+module is loaded, dependencies will be tracked for all commands.
+If any command, its dependencies, or files it generates are missing then
+the target will be considered out-of-date and rebuilt.
+The meta files can also be useful for debugging.
+.Pp
+The build will hide commands ran unless
+.Va NO_SILENT
+is defined.