“realised” means, in relation to an exchange item, where such exchange item is –

 

(a)     a debt in any foreign currency, when and to the extent to which payment is received or made in respect of such debt, or when and to the extent to which debt is settled or disposed of in any other manner;

 

(b)     a forward exchange contract, when payment is received or made in respect of such forward exchange contract;

 

(c)     a foreign currency option contract, when payment is received or made in respect of the right in terms of such foreign currency option contract having been exercised, or when such foreign currency option contract expires without such right having been exercised, or when such foreign currency option contract is disposed of; or

 

(d)     an amount which constitutes a unit of currency, when that amount is disposed of;