In cpdf_add_annotation() ,what's means the param Mode ?

<? $radius = 200; $margin = 20; $pdf = cpdf_open(0); cpdf_set_creator($pdf, "pdf_clock.php3"); cpdf_set_title($pdf, "Analog Clock"); cpdf_page_init($pdf, 1, 0, 2 * ($radius + $margin), 2 * ($radius + $margin), 1.0); cpdf_translate($pdf, $radius + $margin, $radius + $margin); cpdf_save($pdf); cpdf_setrgbcolor($pdf, 200.0, 0.0, 1.0); cpdf_setlinewidth($pdf, 3.0); for ($alpha = 0; $alpha < 360; $alpha += 30) { cpdf_rotate($pdf, 30.0); cpdf_moveto($pdf, $radius, 0.0); cpdf_lineto($pdf, $radius-$margin, 0.0); cpdf_stroke($pdf); } cpdf_circle($pdf, 0, 0, $radius/30); cpdf_fill($pdf); cpdf_restore($pdf); cpdf_finalize_page($pdf,1); cpdf_add_annotation ($pdf,0,0,400,140,"test","Content",200); cpdf_finalize($pdf); Header("Content-type: application/pdf"); cpdf_output_buffer($pdf); cpdf_close($pdf); ?> cpdf_add_annotation ($pdf,0,0,400,140,"test","Content",200); The 200 cann't change any,why? Thanks a lot