Openbox lets you specify whether a calculation is a balance (i.e. a corkscrew) or not. If it is a balance, then it will appear in the spreadsheet as an opening balance, plus or minus some flows, and a closing balance. This means that the formula needs to be structured in a certain way, or Openbox will give you a warning:

1. It needs to include the BEG() function – this means the opening balance.
2. The flows need to be added or subtracted from BEG()

For example the formula for cash might be:

BEG() + [Cash receipts] – [Cash outgoings]

On the other hand, the BEG() function does not make sense unless the calculation is a balance. Only balances have opening balances. So if you include it in another formula, Openbox will warn you about that too.