The legislation is supported by guidance (Wales Office Circulars 61/96 and 1/98) which explains the criteria against which candidate buildings will be assessed.
Mae’r canllawiau (Cylchlythrau’r Swyddfa Gymreig 61/96 a 1/98) sy’n ategu’r ddeddfwriaeth yn esbonio’r meini prawf a ddefnyddir i asesu adeiladau.