code: private static String buildJmolSelection(ResidueNumber[] residues) {
  		StringBuilder cmd = new StringBuilder("select ");
  		for(ResidueNumber res : residues) {
  			if(res != null) {
  				cmd.append(String.format("%d^%s:%s.CA or ", res.getSeqNum(),
  						res.getInsCode()==null?" ":res.getInsCode(),
  								res.getChainName()));
  			}
  		}
  		cmd.append("none;");//easier than removing the railing 'or'
  		return cmd.toString();
  	}
docs: Converts an array of ResidueNumbers into a jMol selection.
  
  <p>For example, "select 11^ :A.CA or 12^ :A.CA;" would select the
  CA atoms of residues 11-12 on chain A.
  @param residues Residues to include in the selection. Nulls are ignored.
  @return