This requirement implies that a budget may be planned at a detailed account level, as it is done once a year while a forecast is done more often. Because of this, it is required that the forecast allow ledger accounts to be more summarized for planning purposes.
Scenario: A pharmaceutical company is preparing its financial forecast. The budget is usually organized according to the structure of the company's chart of accounts. However, when it comes to forecasting, the company wants to summarize certain accounts like Travel Expenses.
Solution: With the CPM software's ability to summarize accounts differently in the forecast, the company consolidates Hotel, Air, Ground Transportation and Per Diem accounts into one Travel account for planning. This makes forecasting faster, as the department heads are not having to consider each and every account that, in the end, does not make a material difference in the accuracy of the forecast.
When the chart of accounts is represented as a hierarchy with expand/collapse functionality, in many cases the user can just collapse an account hierarchy and plan at the summary level. This would just break back the values evenly into the child accounts. If you're looking to summarize the accounts, it really doesn't matter what value the child accounts contain. The only thing that matters is the parent account - Travel in the example above.
However, some tools will not allow data entry at a summarized account. They might require data entry to start at the lowest possible level in the hierarchies. As such, those systems need to have a way to represent accounts and other dimensions in a different way for the forecast.
While this sounds complex, it really isn't. All we're requiring here is a method to forecast at a summarized level.