Just to clarify, using this free data system, you can collect unit movements by inputting a unit number, or see what unit is working a particular service etc??
No - such information is (currently) restricted to internal railway systems
as there is no proven need for the public to have access to it, although it
sounds like Poggs is working to change that!!
But until such time as info is made available to the public, as others
have said, if you are after a particular unit, you either have to go
out 'on spec' and wait for it to turn up or ask nicely on here and
a member of railway staff with access to the appropriate systems
may be able to assist you.
But once you know that a particular unit you want to see is working
a partucular train, RTT and opentimes can then tell you its next working(s),
including empty stock movements.
MARK