[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Z] radio buttons  random URL generator  readability, whitespace and  readonly attribute (form controls)  rectangular image map area  Redirect header  redundant HTML tags  references     to external content      inline      to multimedia elements  Refresh header  rel attribute     <a>      <link>  relationships     between HTML documents      between hyperlinks  relative font size  relative frame sizes  relative URLs  2nd      advantages of using      <base> tags  repeat keyword  repetition grammar rules, elements  Requests for Comments (RFCs)  reserved characters  [See special characters] reset buttons  resizing images  reusing images  rev attribute     <a>      <link>  RFCs (Requests for Comments)  RGB color values  [See also colors]2nd  richness property  ridged borders  right alignment  [See alignment] \:right pseudoclass  rows attribute     <frameset>      <textarea>  rows, creating in tables  [See also tables]2nd  rowspan attribute (<th> and <td>)  ruby text  rules  [See horizontal, rules] rules attribute (<table>)