-echo=string, and sleep=value. Any number of `--checkpoint-action'
-options can be specified, the actions will be executed in order of
-their appearance in the command line.
+echo=string, ttyout=string, exec=cmdline, and sleep=value. Any number
+of `--checkpoint-action' options can be specified, the actions will be
+executed in order of their appearance in the command line. See
+chapter 3.8 "Checkpoints" for a complete description.
+
+* New options --no-check-device, --check-device.
+
+The `--no-check-device' option disables comparing device numbers during
+preparatory stage of an incremental dump. This allows to avoid
+creating full dumps if the device numbers change (e.g. when using an
+LVM snapshot).
+
+The `--check-device' option enables comparing device numbers. This is
+the default. This option is provided to undo the effect of the previous
+`--no-check-device' option, e.g. if it was set in TAR_OPTIONS
+environment variable.