To read the FEM, EVN ,GEV or NAR structures, use a command similar to:
IDL> rd_fem, sttim, entim, fem
IDL> rd_evn, index(0), index(n-1), evn
IDL> rd_nar, '1-nov-91', '2-nov-91', evn
Look at the File Control Document for a description of the structures
which are returned.