The UPN is, as far as possible, a blind number held by schools on the pupil’s electronic record, and only output in specific circumstances.
Cyn belled ag y bo'n bosibl, mae'r RhUD yn rhif cyfrinachol a ddelir gan ysgolion ar gofnod electronig y disgybl, a dim ond dan amgylchiadau penodol y caiff ei rannu.