CURR_MONTH
This parameter states which month to use when fetching the currency rate from the <datacontainer>.currtable. You can only use this parameter in PARAM and you want all values to use the same month. If you want to have different months, you need to add them in the <currency_type>_CURRMONTH parameter in the sheet.
This parameter can only be used in REPORT templates.
For more information, see our article on Currency Calculation.