[%# Produce a URL for a given field that cycles for sorting from
    "nothing" to "ascending" to "descending" then back to "nothing".
%]
[% MACRO sort_url(field)
        IF (CGI.param('sort') == field);
                SWITCH CGI.param('sort_type');
                CASE "asc";
                   mkurl('',{sort=>field, sort_type=>'desc'},1);
                CASE "desc";
                   mkurl('',{sort=>field, sort_type=>'asc'}, 1);
                END;
	ELSE;
           mkurl('',{sort=>field, sort_type=>'asc'}, 1);
	END;
%]
[%# SET click_sort = l("click to sort") %]
[%# SET click_sort = "title=\"$click_sort\"" %]

[%# Produce arrows to indicate the sorting status of the column %]
[% MACRO sort_indicator(field)
        IF (CGI.param('sort') == field);
                SWITCH CGI.param('sort_type');
                CASE "asc";
"&nbsp;<span class=\"column_sort_arrow\">&#9650;</span>";
                CASE "desc";
"&nbsp;<span class=\"column_sort_arrow\">&#9660;</span>";
                END;
        END;
%]

[%# Column headers for sortable columns %]
[% MACRO sort_head(field, field_label)
   BLOCK %]
<a href="[% sort_url(field) %]" [% click_sort %]>[% l(field_label) %]</a>[%- sort_indicator(field) %]
[% END
%]