to a specific final state characterized by a specific final principal quantum number 
in: a characteristic emission spectrum or absorption line spectrum
is: the set of spectral lines which arise when electrons make transitions from initial quantum states characterized by initial principal quantum numbers to a specific final state characterized by a specific final principal quantum number
is exemplified: for the spectrum of atomic hydrogen, by the Lyman series for 
the Balmer series for 
the Paschen series for 
etc.
Copyright 1997, The Open University