docs: def __ilwdchar(self,istr):
      """
      If the ilwd:char field contains octal data, it is translated
      to a binary string and returned. Otherwise a lookup is done
      in the unique id dictionary and a binary string containing the
      correct unique id is returned.
      """
      istr_orig = istr
      istr = self.licrx.sub('',istr.encode('ascii'))
      istr = self.ricrx.sub('',istr)
      if self.octrx.match(istr):
        exec "istr = '"+istr+"'"
        # if the DB2 module is loaded, the string should be converted
        # to an instance of the DB2.Binary class. If not, leave it as 
        # a string containing binary data.
        try:
          istr = DB2.Binary(istr)
        except:
          pass
      else:
        try:
          istr = self.unique.lookup(istr)
        except AttributeError:
          if not self.unique:
            istr = istr_orig
          else:
            raise LIGOLwParseError, 'unique id table has not been initialized'
      return istr