A’ roads are further sub-categorised as ‘A Trunk’ roads (part of the strategic road network owned by and operated on behalf of government) and ‘A county’ roads (all other A roads).
Cafodd y categorïau o grwpiau ethnig, gan gynnwys y categorïau 'eraill' lle y gellir ychwanegu ymateb, eu trefnu o fewn pum categori o grwpiau ethnig lefel uchel.