+<li><a name="rna">RNA Helix</a> (only shown when working with nucleotide sequences)<br>
+<em>Mark selected positions as participating in a base pair
+either upstream or downstream. When the dialog box opens, enter a
+'(' to indicate these bases pair with columns upstream (to right),
+and ')' to indicate this region pairs with bases to the left of the
+highlighted columns.<br />If any brackets do not match up, then an
+orange square will highlight the first position where a bracket was
+found not to match.
+</em>
+</li>