Using the encrypted IRN this core table was then linked to two other education tables, namely the Pupil Level Annual School Census (PLASC) and Educated Other Than At School (EOTAS) datasets.
Roedd y datganiad blaenorol yn cysylltu'r Rhestr Gwarchod Cleifion â'r Cyfrifiad Ysgolion Blynyddol ar Lefel Disgyblion (CYBLD) gan ddefnyddio cyfenw a chod post.