17. For the purpose of determining or redetermining—
(a)budget shares for nursery schools maintained by them;
(b)amounts to be allocated in respect of nursery classes in schools maintained by them;
(c)amounts to be allocated to relevant early years providers in their area;
(d)amounts to be allocated to exempt early years providers in their area; and
(e)amounts to be allocated in respect of community early years provision in schools maintained by them,
a local authority may use factors or criteria which differentiate between different categories or descriptions of school or provider on the basis of unavoidable costs.