A change to reporting guidance led to the inconsistent implementation of a data standard change notice across health boards in Wales between March 2021 and October 2021.
Arweiniodd newid i ganllawiau adrodd at fyrddau iechyd yn rhoi hysbysiad newid safon data ar waith mewn ffordd anghyson yng Nghymru rhwng mis Mawrth 2021 a mis Hydref 2021.