Particularly for Sage 200 end users, you may be more used to seeing an IF statement lay out as below:

          If ( SOPInvoiceCredit.SOPInvoiceCreditTypeID = 0,  1, -1 )  * SOPInvoiceCredit.InvoicedGrossValue

This is how excel and indeed the old Report Designer (Pre 2010) would require an IF statement to be entered.

Below is how you would now enter the expression:

          (SOPInvoiceCredits.SOPInvoiceCreditTypeID = 0 ? 1 : -1) * SOPInvoiceCredits.InvoicedGrossValue

In this example we have said If the SOPInvoiceCreditTypeID is  0, multiply the InvoicedGrossValue by 1, otherwise multiply it by -1.

This expression would be used when trying to determine if the value on a SOP report is Positive or Negative, where the report is using the Type of transaction therefore displaying everything as Positive.