sdf ::=
 
  SDF ( [ field_name | CONSTANT filename ] [os_file_proc_clause] [READSIZE size] 
 
 [CHARACTERSET name] [LENGTH [SEMANTICS] {BYTE | CHAR | CHARACTER}] 
 
 [BYTEORDER { BIG | LITTLE } [ENDIAN]] [BYTEORDERMARK { CHECK | NOCHECK }] [delim_spec] )