Get data from DSN.
3913 INQUIRE(file=filename,exist=exist)
3917 if (lwipe.or..not.exist)
then 3921 call l4f_category_log(dbasession_init%category,l4f_info,
"file exists; appending data to file")
3924 if (.not.exist)
then 3925 call l4f_category_log(dbasession_init%category,l4f_error,
"file does not exist; cannot open file for read")