My 2 appendices are <topicref>'s in backmatter. <backmatter>     <topicref href="A.dita" type="topic"></topicref>     <topicref href="B.dita" type="topic"></topicref></backmatter> Appendix A      I want the page numbering to show in the footer "A-1, A-2, A-3..." for appendix AAppendix B      and "B-...