It includes both primary legislation (this an Act of either the UK Parliament or the Welsh Parliament) and secondary legislation in the form of regulations, orders or statutory codes.
Mae’n cynnwys deddfwriaeth sylfaenol (sef Deddf gan Senedd y DU neu Senedd Cymru) ac is-ddeddfwriaeth ar ffurf rheoliadau, gorchmynion neu godau statudol.