Annual compensation. (156) as set out above, the authority is at this stage of the view that at least a large part of the compensation that aS Oslo Sporveier and aS Sporveisbussene have received has been awarded in line with the existing aid scheme, which provides in essence for loss coverage for the public service. Such a scheme would appear to presuppose the separation of accounts, an appropriate allocation of common costs and arms-length intra-group transactions for undertakings that in addition to providing public services also engage in commercial activities. Complying with these principles seems necessary to avoid that aid is granted outside the scheme.