Fractions and Commodities and Accounts, Oh My!

[David Brock]

Ugh.  I'm still trying to figure out the relationship between commodity 
and account (I know that one trades in the other).

Let's say I have a commodity called FundABC that trades in thousandths.  
So, I have specified "1/1000" as the "fraction traded":

Commodity- FundABC
fraction traded: 1/1000

Then, I have, in my Brokerage Account, a sub-account called FundABC, 
which trades in commodity "FundABC"

Assets (Comm: $CAD)
Assets:Chequing (Comm: $CAD)
Assets:Brokerage (Comm: $CAD)
Assets:Brokerage:FundABC (Comm:FundABC)

This account has a selector that allows me to change the "fraction 
traded" including an option to "Use commodity value".  That's what it's 
set to.

To add to the complexity, I have another account that holds the same 
fund that trades in the same commodity, but may have been set up 
originally with a different value in the (account) "fraction traded":

Assets:BrokerageRSP (Comm: $CAD)
Assets:BrokerageRSP:FundABC (Comm:FundABC)

I'm not exactly sure of the relationship here, including the fraction 
traded, but I suspect it may be a bad thing (tm) if the fraction traded 
is different in one account from another, when the commodity is the same.

Can I change the "fraction traded" of an account?  I know that I can 
change it, but I'm wondering if this might be the source of some 
inconsistencies in my data.  I have changed it, but I think some 
transactions don't reflect the change.  The values in the xml file 
appear to all be fractions, for which the denominator is the fraction 
traded (I think) but, changing the fraction traded of an account seems 
to take place instantly, with no delay to make the appropriate changes 
in the data.  Let me re-phrase:  The act of changing the fraction traded 
appears to be a simple account setting, not an "adjustment to the 
transactional data".  Since it will likely be asked, the reason for the 
change to the fraction traded is really to make it match the commodity.  
The accounts & commodities were all imported, and it appears that it 
wasn't done perfectly.

 From that... can someone explain the reasoning behind the "commodity 
fraction traded" vs "account fraction traded", ie, why would I ever want 
to have an account that trades in numbers that aren't exactly that of 
the commodity?

Thanks to anyone who takes the time...