In order to read the data into IDL session, give the file name as follows:
IDL> file='./if911202'
IDL> nori_rd_dat,file,index,data CR
In order to read the data in specified duration:
IDL> timerange=['1991-12-2 2:00','1991-12-2 4:00'] CR
IDL> nori_rd_dat,file,index,data,timerange=timerange CR