The example below combines protocol for parallel segmentation and drama. Is there a better way to do this that is still P5-conformant? I suppose I could dump @who on <sp/>, but I'd rather not. I've tried some other nestings, but none is valid as far as I can see.

                  <!-- Some text. -->                  
                     <sp who="#ovines" corresp="line21">
                        <!-- Note that in #w only the speech prefix is "Sheep". -->
                              <rdg wit="#w">Sheep</rdg>
                              <rdg wit="#b">Ovines</rdg>
                              <rdg wit="#p">Ovines</rdg>
                        <l n="21">
                              <rdg wit="#w">Baa.</rdg>
                              <rdg wit="#b">Baaa!</rdg>
                              <rdg wit="#p">Baaa.</rdg>
<!-- More of the same. -->