Data Management - Passing Start Period and End Period to Business Rules

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In Data Integration I have a business rule that performs calculations post load for the period range loaded i.e. DM POV Start and End Period range.  In DM Cloud, there is an option to select period (but it defaults to the start period - refer to attached screenshot). 

Would be great if there was an option to select the start and end periods separately.

Does anyone know of a way within DM to select start and end periods.

I have tried custom option value of $START_PERIODKEY[MMM]$ and $END_PERIODKEY[MMM]$  (as we can do for ERP intergration options).