Whenever a commodity is purchased using a different commodity (such as
a share of common stock using dollars), it establishes a price for
that commodity on that day.  It is also possible, by recording price
details in a ledger file, to specify other prices for commodities at
any given time.  Such price transactions might look like those below:

@smallexample
P 2004/06/21 02:17:58 TWCUX $27.76
P 2004/06/21 02:17:59 AGTHX $25.41
P 2004/06/21 02:18:00 OPTFX $39.31
P 2004/06/21 02:18:01 FEQTX $22.49
P 2004/06/21 02:18:02 AAPL $32.91
@end smallexample

By default, ledger will not consider commodity prices when generating
its various reports.  It will always report balances in terms of the
commodity total, rather than the current value of those commodities.
To enable pricing reports, use one of the commodity reporting options.