Parameters for this report include:
The start and end dates of the accounting period.
The length of each "step", or interval in the account period.
The accounts for which the report is to be produced. If more than one account is selected, the sum of all balances of accounts selected is used FIXME: Could somebody make sure this is right?
Which aspect of the report is to be graphed. There are three graphs available:
Average Balance during interval
Net Gain/Loss over interval
Gains and losses over interval