The panel bases their decisions on a set of guidelines (currently dating to June 2023), specific to Welsh settlement names (such as those of villages, towns, and cities) and topographic features (such as lakes, mountains and rivers).
The panel tries to follow Welsh language orthography, and recognises the authority of Geiriadur Prifysgol Cymru (The University of Wales Dictionary of the Welsh Language) on the matter, following the form the dictionary provides as much as possible.
However, the panel decided to recommend the use of a circumflex (long sign) for some names, even if not a Welsh orthographical standard, to "avoid ambiguity and ensure correct pronunciation".
[3] The guidance also explained when the panel is to recommend the use of hyphens, an apostrophe or diaeresis, one vs. two words, the use of the Welsh definite article (y/yr/'r), and its relation to emphasis, place-names named after persons, creating new names, recognising local dialects, and dual forms (closely related English and Welsh versions).
For English place-names in Wales referring to saints, the guideline also recommends standardisation, for example, St Davids.
[12] The Commissioner also advises local authorities or housing developers to avoid mutating place names and integrating the Welsh definite article (y/yr/'r), on road signs in Wales, and to maintain the unmutated form of the name in both languages on signage.
The Commissioner only recommends what place-names can be standardised, local authorities hold the responsibility to update signage.