Mae’r Mesur yn cyfeirio at bobl dan 18 oed fel “plant”  a’r rhai rhwng 18 a 24 oed (gan gynnwys y rheini sy’n 24 oed) fel “pobl ifanc”. Mabwysiadwyd y dull hwn er mwyn bod yn gyson â’r CCUHP ac â Mater 15.6 yn Atodlen 5 i Ddeddf Llywodraeth Cymru 2006, y deilliodd cymhwyster deddfwriaethol ar gyfer y Mesur hwn ohono.
The Measure refers to people aged under 18 as “children” and those aged 18-24 (including those aged 24 years) as “young persons”. This approach has been adopted in order to be consistent with the (UNCRC) and with Matter 15.6 in Schedule 5 to the Government of Wales Act 2006, from which the legislative competence for the Measure was derived.