Mae mudo graddol eisoes ar y gweill, gyda 'Stop Sell' Cenedlaethol i'w weithredu erbyn mis Medi 2023. Mae 'Stop Sell' yn derm a ddefnyddir pan fydd cyfyngiadau ar gyflenwad newydd a'r hyn y gellir ei wneud ar linellau sy'n bodoli eisoes.
A phased migration is already underway, with a National 'Stop Sell' to be implemented by September 2023. ‘Stop Sell’ is a term used when there are limitations on new supply and what can be done on existing lines.