The ALN system started on 1 September 2021, and 1 January 2022, for children up to and including Year 10 who were newly identified as having ALN after those dates.
Dechreuodd y system ADY ar 1 Medi 2021, ac 1 Ionawr 2022, ar gyfer plant hyd at a chan gynnwys Blwyddyn 10 a oedd newydd gael ADY ar ôl y dyddiadau hynny.