A common problem with dummy timescales is that you cannot use the Previous() function to create a rolling balance. In this example I have exchange rates which are only provided on week days (on a dummy daily timescale of YYYYMMDD). I need a rolling balance to ensure that all days have an exchange rate.
To produce the rolling balance on a dummy timescale we can use the cumulate() function, with a reset condition on where the value of the periodic balance is not equal to zero. This means that whenever the periodic number changes we show the new value and carry it forward until this changes.
Anaplan Formula for line item (High All):
CUMULATE(High All Current Period, High All Current Period <> 0, Day List)