What is function/meaning of string arg to DataReferenceImpl()?

Can anyone tell me what the purpose of the string argument to DataReferenceImpl() is? I've seen it used in several programs like this Jython snippet:

t_h_ref = DataReferenceImpl("t_h_ref")

The point here is that string appears to be always the same as the name of variable in the programming language. Can be an arbitrary string? What is it used for? What happens if I leave it blank? How about if I use the same string for several variables? (like this Jython again)

t_h_ref = [] # Empty array
for i in range(10):
        t_h_ref.append(DataReferenceImpl("t_h_ref")

Thanks,

-Frank

PhD, Computational Biologist,
Harvard Medical School BCMP/SGM-322, 250 Longwood Ave, Boston MA 02115, USA.
Tel: 617-432-3555 Fax: 617-432-3557 http://llama.med.harvard.edu/~fgibbons