[%-# '<=prev | up | next=>' chapters navigation bar
   # if there is no up, prev or next we render only a transparent placeholder
   # expects to be set 
   # nav          - cache navigator object
   # rel_doc_root - relative docs path
-%]
[%- prev = nav.prev;
   next = nav.next;
   IF prev;
       prev_link = INCLUDE link prefix=rel_doc_root link=prev.meta.link;
   END;
   IF next;
       next_link = INCLUDE link prefix=rel_doc_root link=next.meta.link;
   END;
-%]
[%- IF prev_link || next_link || (rel_doc_root && rel_doc_root != '.') -%]
    [%- IF prev_link -%]
<a href="[%- prev_link -%]"><img src="[%- doc.dir.abs_doc_root -%]/images/nav/page_prev.gif" alt="previous page: [% prev.meta.title | html %]" border="0" width="48" height="20"></a>
    [%- ELSE -%]
<img src="[%- doc.dir.abs_doc_root -%]/images/nav/page_noprev.gif" alt="no previous page" border="0" width="48" height="20">
    [%- END -%]
    [%- IF rel_doc_root -%]
<a href="[%- rel_doc_root -%]/index.html"><img src="[%- doc.dir.abs_doc_root -%]/images/nav/page_parent.gif" alt="page up: [% nav.up.meta.title | html %]" border="0" height="20" width="25"></a>
    [%- ELSE -%]
<img src="[%- doc.dir.abs_doc_root -%]/images/nav/page_noparent.gif" alt="no parent page" border="0" height="20" width="25">
    [%- END -%]
    [%- IF next_link -%]
<a href="[%- next_link -%]"><img src="[%- doc.dir.abs_doc_root -%]/images/nav/page_next.gif" alt="next page: [% next.meta.title | html %]" border="0" width="48" height="20"></a>
    [%- ELSE -%]
<img src="[%- doc.dir.abs_doc_root -%]/images/nav/page_nonext.gif" alt="no next page" border="0" width="48" height="20">
    [%- END -%]
[%- ELSE -%]
<img src="[%- doc.dir.abs_doc_root -%]/images/trans_pix.gif" alt="navigation" border="0" width="123" height="20">
[%- END -%]