-If the source system is a daemon using chroot, or if a user or group
-name does not exist on the destination system, then the numeric ID
-from the source system is used instead.
+If a user or group has no name on the source system or it has no match
+on the destination system, then the numeric ID
+from the source system is used instead. See also the comments on the
+"use chroot" setting in the rsyncd.conf manpage for information on how
+the chroot setting affects rsync's ability to look up the names of the
+users and groups and what you can do about it.