Field help (ENVFIYSTR) 

Start date of the FY budget. Date loaded, cannot be modified, for the start date of the budget envelope for an annual envelope. For a pluriannual envelope, this date is loaded (and cannot be modified) by the start date of the envelope if the budget corresponds to the first budget of the envelope. For following budgets, this date is loaded (and cannot be modified) by the start date of the FY.