--- mount/mount.8
+++ mount/mount.8
@@ -1781,6 +1781,12 @@
 .TP
 .B dmapi " / " xdsm
 Enable the DMAPI (Data Management API) event callouts.
+Use with the "mtpt" option.
+.TP
+.BI  mtpt= mountpoint
+Use with the "dmapi" option. The value specified here will be
+included in the DMAPI mount event, and should be the path of
+the actual mountpoint that is used.
 .TP
 .BI logbufs= value
 Set the number of in-memory log buffers.