As well as the local list, there is also a ‘central list’, which covers certain cases where property crosses billing authority boundaries, for example, railways, pipelines and water infrastructure.
Yn ogystal â'r rhestr leol, mae ‘rhestr ganolog’ hefyd, sy'n cwmpasu achosion penodol lle mae eiddo yn croesi ffiniau awdurdodau bilio, er enghraifft, rheilffyrdd, piblinellau a seilwaith dŵr.