Some further multiple currency queries

[Nicholas Lee]

Hey, just a quick follow up query on the multiple
currency GL discussion we had back in November
(http://kt.zork.net/GNUe/gnue20021109_54.html#11).

What happens when your base currency is, say GBP, but you transfer
amounts from a USD to a EUR account?

Obviously the (txn_curr_amt, fgn_curr_amt, fgn_curr) tuple is sufficent
to expression this transaction. You expect that it would require two
balanced tuples, eg.  
  (-1100, -1000, USD)
  ( 1100,  2000, EUR) 

To get some sort of (1000, 2000, USD:EUR) equilavent, ignoring the
reality of exchange rates at the moment.


The problem I see from a user-interface point of view is that its fair
enough to ask the user or generate implicitly from amounts for the
USD:EUR ratio. That however doesn't give either one of the USD:GBP and
GBP:EUR ratios.

Is there a general rule of thumb to deal with this, that keeps the
simple power of the system you explained? Or is it a a mess of "special
cases."



Nicholas