Determine Retroactive Payroll Run or Regular Calculate Payroll Run in Payroll Fast Formula?

Within a fast formula, how can we determine if the formula is being run in retroactive payroll or regular payroll?

Our retirement fast formula is used in the Recalculate Payroll for Retroactive Changes and regular Calculate Payroll flows.

We need to be able to determine whether the fast formula is being run in the retro flow versus the regular payroll flow. This determines which balance to multiply by the retirement rate to get the retirement amount.

In the retro run, we want all retirement eligible element entry amounts to be multiplied by the rate, including retro elements from previous retro runs. In the regular payroll run, however, the balance should only contain current eligible element entry amounts to avoid paying the retro payment amount twice.