listbox handling

ive appended the value-key set into listbox as:

select * from zda_sntype into table lt_zda_sntype.

name = 'PS_PARM'.

loop at lt_zda_sntype into wa_zda_sntype.

value-key = wa_zda_sntype-santyp.

value-text = wa_zda_sntype-txt30.

append value to list.

endloop.

call function 'VRM_SET_VALUES'

exporting

id = name

values = list.

lst_flg = 1.

endif.

HOW TO GET THE SELECTED VALUE, At runtime....????