Igama elithile “iingcingo ezine” ibhekisa kwiingcingo ezintathu eziphilileyo kunye nocingo olunye olungathathi hlangothi, ibhalwe njengo A|B|C|N|, nge-N emele ucingo oluphantsi.
Iingcingo ezintathu eziphilayo kufuneka ziqhagamshelwe kwingeniso ephezulu yokutshintsha okuphambili kwibhokisi yokusasaza enobungqina bokudubula., kunye nocingo olungathathi hlangothi kufuneka ludibaniswe ngokuthe ngqo kwi-terminal bar engathathi hlangothi ngaphandle kwefuse. Zonke ezinye iiswitshi kunye nezixhobo zombane kufuneka zifakwe kwiintambo ukusuka kwisiphumo esisezantsi sokutshintsha okuphambili.