"levy"

means an amount payable at intervals or at specified times by specified persons and based on—

(a)        one or more of the following criteria, namely—

(i)        gross tonnage of ship;

(ii)        category of ship;

(iii)        category of cargo;

(iv)        age of ship;

(v)        nationality of ship;

(vi)        frequency of port calls by ship; and

(b)the presence of ships in the internal or territorial waters of the Republic otherwise than in innocent passage;