-Shift each line in the region by a fixed distance, to the right or
-left (@code{indent-rigidly}). The distance to move is determined by
-the numeric argument (positive to move rightward, negative to move
-leftward).
-
-This command can be used to remove all indentation from the lines in
-the region, by invoking it with a large negative argument,
-e.g., @kbd{C-u -1000 C-x @key{TAB}}.
+This command is used to change the indentation of all lines that begin
+in the region, moving the affected lines as a ``rigid'' unit.
+
+If called with no argument, the command activates a transient mode for
+adjusting the indentation of the affected lines interactively. While
+this transient mode is active, typing @key{LEFT} or @key{RIGHT}
+indents leftward and rightward, respectively, by one space. You can
+also type @kbd{S-@key{LEFT}} or @kbd{S-@key{RIGHT}} to indent leftward
+or rightward to the next tab stop (@pxref{Tab Stops}). Typing any
+other key disables the transient mode, and resumes normal editing.
+
+If called with a prefix argument @var{n}, this command indents the
+lines forward by @var{n} spaces (without enabling the transient mode).
+Negative values of @var{n} indent backward, so you can remove all
+indentation from the lines in the region using a large negative
+argument, like this:
+
+@smallexample
+C-u -999 C-x @key{TAB}
+@end smallexample