-where what is is either "\fBall\fR" or "\fBmain\fR".
-Using "\fBall\fR", all files are overwritten during a batch export, otherwise
-only the main file will be. When this switch is followed by anything else other
-than "\fBall\fR" or "\fBmain\fR", the behavior is as if "\fBall\fR" was
-specified, but what follows is left on the command line for further processing.
+where what is is either "\fBall\fR", "\fBmain\fR" or "\fBnone\fR".
+Specify "\fBall\fR" to allow overwriting all files during a batch export,
+"\fBmain\fR" to allow overwriting the main file only, or "\fBnone\fR"
+to disallow overwriting any file. When this switch is followed by anything
+else other than "\fBall\fR", "\fBmain\fR" or "\fBnone\fR", the behavior is as
+if "\fBall\fR" was specified, but what follows is left on the command line for
+further processing.