diff --git a/xorriso/xorriso.1 b/xorriso/xorriso.1
index a2913231..ebbd88f0 100644
--- a/xorriso/xorriso.1
+++ b/xorriso/xorriso.1
@@ -1835,9 +1835,12 @@ on media and if the expected changes are much smaller than the full backup.
 An update run will probably save no time but last longer than a full backup.
 .br 
 With overwriteable media like DVD+RW or disk files, the older backup versions
-cannot be retrieved. But with multi-session media and mount option "session="
+cannot be retrieved. But with multi-session media and mount option "sbsector="
 it is possible to access the session trees which represent the older backup
-versions. 
+versions. sbsector of a session is its "data   lba:" number from xorriso
+option -toc.
+With CD media, Linux mount accepts session numbers directly by its option
+"session=".
 .br
 \fBDo not write more than about 50 sessions\fR to one multi-session media.
 Theoretical limits are higher but in practice the media deteriorate more early.