EBU Single Rulebook Q&A 11 September 2015 2015_2294 How to manage different local rating scales

With reference to 1cRating 1d field (template 103 13 Annex IV, column No 50) how the different local rating scales must be treated for consolidated reporting, i.e: If a master scale is available at Group level (e.g. for Pillar III purposes), does the Institution have to adopt it, or it can choose to create an ad hoc master scale?