▁occur ▁in ▁Fl am boy ant ▁architecture , ▁such ▁as ▁in ▁the ▁ ▁Church ▁of ▁Saint - Pierre ▁in ▁Ca en . ▁ ▁The ▁v ault - plan ▁diagram ▁of ▁E ly ▁Ch oir ▁shows ▁the ▁rib s ▁as ▁double ▁lines . ▁The ▁main ▁longitud inal ▁r idge ▁rib ▁( middle ▁vertical ▁lines ) ▁and ▁trans verse ▁r idge ▁rib s ▁( altern ate ▁horizontal ▁lines ) ▁intersect ▁each ▁other ▁at ▁the ▁central ▁b oss es ▁( large ▁circles ). ▁The ▁longitud inal ▁r idge ▁rib ▁runs ▁down ▁the ▁centre ▁of ▁the ▁ ▁cho ir , ▁and ▁the ▁trans verse ▁r idge ▁rib s ▁span ▁from ▁the ▁a pe x ▁of ▁each ▁window ▁at ▁the ▁sides ▁of ▁the ▁cho ir . ▁Arch ed ▁diagonal ▁rib s ▁span ▁from ▁pi ers ▁between ▁the ▁windows , ▁from ▁spring ers ▁to ▁the ▁central ▁b oss es , ▁and ▁arch ed ▁trans verse ▁rib s ▁( altern ate ▁horizontal ▁lines ) ▁span ▁from ▁the ▁spring ers ▁to ▁the ▁main ▁longitud inal ▁r idge ▁rib . ▁Second ary ▁arch ed ▁diagonal ▁rib s , ▁called ▁tier cer ons , ▁span ▁from ▁the ▁spring ers ▁to ▁the ▁trans verse ▁r idge ▁rib s . ▁L ier nes ▁( sh aded ▁black ) ▁span ▁between ▁the ▁other ▁rib s , ▁forming ▁intr icate ▁pattern ing . ▁ ▁Note : ▁in ▁French ▁termin ology ▁rel ating ▁to ▁architecture , ▁a ▁li erne ▁is ▁a ▁r idge ▁rib , ▁and ▁hence ▁has ▁a ▁different ▁meaning . ▁ ▁See ▁also ▁ ▁V ault