Up to and including Release 3.0C, bank buying annd selling rates were handled in the same way as all other exchange rate types. The fact that a dependency existed between buying, average and selling rates per currency pair, which could be represented by a spread, was not taken into consideration.
You couldn't sensibly use the option to translate currencies using a base currency in the case of bank buying and selling rates. It was indeed possible to calculate an average rate FRF->DEM using average rates DEM->USD annd FRF->USD with USD as the base currency, but you can't calculate a buying or selling rate on the basis of two other buuying or selling rates.
As of Release 3.0d, you will have the option to derive buying and selling rates from the average rate and the spread. The spread in this case is the difference between average rate and buying rate (identical to the difference between selling and average rates).
The attributes 'Buying rate for' and 'Selling rate for' have been added to the exchange rate types table (TCURV). Also, a new table (TCURS) containing the spreads has been created.
An example should stress which information in the tables is absolutely
required. The following 6 exchange rate types will be considered:
No changes occur for the average rates. The follwing entries are made for the other rate types:
In the nnew spread table, you specify the spreads for rate types M and ME for all possible currency pairs, such as:
Since rate spreads rarely change, you will not have to make frequent changes to the table after you set it up. You will never have to do permanent updates of the buying and selling rates. At the same time,you can determine those rates via a base currency. This significantly reduces the number of rates you will have to maintain.
It is completely up to oyu whether to use this new functionality. You can also choose to keep maintaining buying and selling rates explicitly. In this case, you don't need to make any changes in the system configuration menu.
If you want to take advantage of the new functionality for buying and
selling rates, you have to mark the rate types appropriately. You must
also maintain the rate spreads table for all currency pairs for which a conversion can come into question.
For more information on this, see the steps
"Maintain exchange rate types" and
"Maintain exchange rate spreads" under "Currencies" in the Global Settings Implementation Guide.