Distance restriction do have two meaning: Getting unreserved ticket for purpose of boarding SL/AC Coach & get TTE issue fare difference receipt, while other been reservation restriction between two station!!
For Train in starting or end leg, they can have booking option open for various station combo. Like the train do have designated quota for MB/BE & hence the berth designated from MB/BE Onwards can be booked from NDLS-MB/BE!!
But if fellow need to board train with unreserved ticket, distance restriction gets applied, failing which, TTE will calculate Fare distance for minimum restriction...
more... (which definitely will be station after the minimum restriction criteria)!!
PS: Earlier, this train did have restriction from start to end station (which clearly illustrates for unreserved travelers)!!