OK to have a minimum balance requirement on FSA carryovers?

[Atila]

May an employer impose a minimum balance requirement on the amount that an employee/participant may carryover from year to year in an FSA?

For example, can an employer require that to carryover a remaining balance at the end of year 1 into year 2 the employee must have a minimum carryover balance of $10?

I have reviewed Notice 2013-71 and other guidance- there appears not to be a direct answer on this. Any thoughts would be appreciated.