diff --git a/usr.sbin/mountd/exports.5 b/usr.sbin/mountd/exports.5
--- a/usr.sbin/mountd/exports.5
+++ b/usr.sbin/mountd/exports.5
@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd April 16, 2024
+.Dd October 08, 2024
 .Dt EXPORTS 5
 .Os
 .Sh NAME
@@ -170,8 +170,23 @@
 The colon separated list is used to specify the precise credential
 to be used for remote access by root.
 The elements of the list may be either names or numbers.
-Note that user: should be used to distinguish a credential containing
-no groups from a complete credential for that user.
+Note that
+.Cm user:
+should be used to specify a credential containing no groups, in which case the
+established credential will use
+.Ql nogroup ,
+else 65533
+.Pq Dv GID_NOGROUP ,
+as the fallback group
+.Pq a credential object must have at least one group internally .
+Using just
+.Cm user
+.Pq without colon at end
+falls into the
+.Sm off
+.Fl maproot Li = Sy user
+.Sm on
+case described above.
 The group names may be quoted, or use backslash escaping.
 .Pp
 .Sm off