tab_hline (table, TAL_2, 0, tab_nc (table) -1, column_headers);
tab_vline (table, TAL_2, row_headers, 0, tab_nr (table) - 1);
tab_hline (table, TAL_2, 0, tab_nc (table) -1, column_headers);
tab_vline (table, TAL_2, row_headers, 0, tab_nr (table) - 1);