was modified between BEG and END. PROPERTY is the property name,
and VALUE is the old value.
-An entry (FUN-NAME . ARGS) means undo the change with (apply FUN-NAME ARGS).
+An entry (apply FUN-NAME . ARGS) means undo the change with
+\(apply FUN-NAME ARGS).
+
+An entry (apply DELTA BEG END FUN-NAME . ARGS) supports selective undo
+in the active region. BEG and END is the range affected by this entry
+and DELTA is the number of bytes added or deleted in that range by
+this change.
An entry (MARKER . DISTANCE) indicates that the marker MARKER
was adjusted in position by the offset DISTANCE (an integer).