It also provides an overview of what changes have been made in nine local authorities across England and Scotland, and the consultation process involved with these changes.
Mae hefyd yn rhoi trosolwg o'r newidiadau a wnaed mewn naw awdurdod lleol ledled Lloegr a'r Alban, a'r broses ymgynghori sy'n gysylltiedig â'r newidiadau hyn.