Kindly check theory with reality & find whats true!!
This UP & DN issue has been mugged many times!!
Only one thing was close enough & that was, if number even, train is Down, while if its Odd, train is up.
But to hamper this logic, SLN-AII & PNBE-INDB Express prevail.
So...
more... only one hard n fast logic, train running on UP Track or UP direction or UP, indifferent to serial number, Home Return or other related logic!!